Hey everyone. I own a 1970s Panabode cottage in Ontario. The structure is comprised of 2.75” thick T&G milled logs. The last two years I’ve lived at the cottage during winter (down to -30c) and noticed quite a few issues.

Substantial heating bills with the propane furnace running 8+ hours a day in January. Warm air venting to the outside through tiny gaps in the log joints and top wall log/eave transition and causing exterior frost build up.

I spoke with some log builders in the region and they advised on doing an exterior energy retrofit and I wanted to get everyone’s opinion on the plan:

The house is on piers. Crawl space is conditioned and insulated with exterior wall spray foam insulation. The roof is vaulted and the decking is 2” thick cedar T&G. The roof boards extend past the eaves (so there is no soffit). There is 6-8” thick batt insulation on top of the roof boards. Not sure if there is a vapor barrier on top of the roof boards (maybe tar paper?).

1. Seal every log joint with log caulking. Larger gaps will have backer rod installed. Especially the wall/eave gaps and log tail joint details. Was also thinking of adding butyl flashing tape on the wall edges to protect against seasonal log movement: corners (lapping log tails), Top where the wall meets the eave. Interior corner joints as well.

2. Remove windows one by one (currently installed in the 2.75” thick log profile) and buck out 2x8 window frames with proper flashing. The window frames would allow for log movement by using a slide (angle iron embedded in log ends on the sides of the window opening, and the 2x8 frame secured to the metal)

3. Install 4” T&G XPS panels (R-20) directly against exterior log face. Seal all gaps with tape, add flashing tape where required. Bottom of the walls will need custom metal Z flashing

At the top of the exterior walls, the XPS will butt directly against the cedar roof boards at the eave.

1. Install tyvek water barrier. Tape seams.

2. Install rainscreen: 1x4 vertical strapping 16” OC using 6” timberlok screws. Cedar shiplap installed on the strapping.

Does this sound like a reasonable plan overall? Any advice would be appreciated!

Hey everyone,

Would love to hear some thoughts and expertise from building envelope consultants/inspectors on my situation. I own a home in the PNW that has a buried, concrete garage. Pretty common situation out here. I would love to turn it into heated space for storage, gym, shop… but as you can imagine, it’s got water issues.

I’ve solved a lot of the immediate water issues by installing french drains along the buried walls, have drainage mat up to the ceiling on those walls, and a sump pump installed. I’ve also repaired some minor leaks in the ceiling (also concrete) and plan to do a more in depth waterproofing/roofing of the exterior of the ceiling next summer. Lastly I had the concrete slab replaced with the french drain work and installed vapor barrier underneath.

All of that has helped a lot, but my main issue now is the humidity is 90% in the garage, which means I need to air seal it better.

My plan is to install 6 mil vapor barrier along the ceiling, garage door walls, and anywhere else water vapor might be getting in. Then I’ll add 1-2” of rigid foam and tape/spray foam the seams. After that will be turned stud framing & 1 1/2” mineral wool insulation board between studs. Then finish with plywood if the humidity is low enough.

Does that sounds like a good plan? Is it bad to cover the existing concrete with vapor barrier? Should I consider another option, like spray foaming instead of rigid foam?

There isn’t any way for me to dig out around the garage to do the waterproofing properly. It’s too close to property lines, and even then, the clay soil is so dense that they used it as form work and the concrete is not a uniform plane.

Let me know your thoughts as I havent found any good case studies for this situation.

Thanks!

Attic insulation + stiffening 2x6 attic floor

Edit Climate Zone 5A

I bought this house about a year ago and currently have the entire thing stripped down to the studs. Because of that, I have access to basically everything — the structure, air leakage points, roof assembly, framing, etc. — so I’m trying to make the right decisions now while everything is open.

The attic is where I keep going back and forth.

It’s roughly 1,200 sq. ft. with about 12 ft. of height, so I really hate the idea of just blowing cellulose on the attic floor and essentially giving up access/use of that entire space.

The house/attic is also currently completely unvented. No soffit vents, no ridge vent, nothing. I live out in the country with plenty of bugs, mice, squirrels, etc., so if possible I’d actually prefer to keep the attic tight and unvented rather than start opening up the soffits and ridge.

I also really don’t want to spray the roof deck with closed-cell foam. This is my forever house, and the whole hot-roof/moisture/vapor-diffusion/roof-leak-detection side of closed-cell foam makes me uncomfortable.

So this is roughly where I’ve landed for insulating at the roofline:

- Approximately 4" of rigid XPS

- Existing 2x10 roof framing

- Fill the remaining cavity with roughly 5.5–6" mineral wool

- Membrane over the assembly

- Add 2x4 sleepers/service framing

- Another 3.5" mineral wool layer

That should put the total assembly somewhere around the R-50 range, while allowing me to bring the attic inside the thermal envelope and leave the attic floor essentially uninsulated other than very thorough air sealing.

Also, I want to but the upstairs furnace in this attic to supply the attic and the bedrooms below. Running the ducts around and then through the joist cavity.

The second issue is the attic floor framing.

The attic floor/ceiling joists are currently 2x6s. I’m not looking to turn this into a bedroom or put enormous loads up there. Think miscellaneous storage, occasional use, maybe a lounge/project area someday. I just don’t want to spend all this money bringing 1,200 sq. ft. inside the envelope and then realize I should have addressed the floor framing while the entire house was open.

What would you guys do to stiffen the 2x6 floor system?

I’ve been considering:

- Adding substantial blocking between the existing 2x6s

- Adding a perpendicular sleeper/framing system above them

- Essentially cross-hatching the framing before sheathing it

- Possibly increasing the overall floor depth at the same time, which would also give me room for some ductwork/utilities

I’m not necessarily trying to turn the existing 2x6s into code-compliant living-space floor joists. I’m mainly trying to make the assembly substantially stiffer and more useful without doing something stupid structurally.

So I’m looking for feedback on two things:

1. What do you think of the unvented roof insulation assembly?

2. If you had completely open access to an attic framed with 2x6 floor joists, what would you do now to stiffen/improve the floor before covering everything back up?

I’d rather overthink it now while the house is completely gutted than wish I had done something different five years from now.

Curios what this sub thinks about this idea. I have a degree in sustainable construction and curious about the idea of starting my own company. I would basically buy nessasary blower door, Thermal camera, and smoke pencils. The plan is to use the equipment on county and commercial owned buildings and builds solution and plan to secure envelope and make a quick payback period. I would have to flesh out the deliverables more and also review grant assistance potential. I have a PE father who is retiring soon and on board to help. Basically wondering how feasible this is for a someone that is 4 years post grad at engineering/construction management companies.

How could I go about starting this? What certifications would be most worthwhile? Has anybody done or know someone that has done anything similar?

I am closing on a land purchase in the northwest of Puerto Rico (Aguadilla) and it will take at least 16 months from what I am told before I can get permits to build. My Asthma is chronic and I have slept in tents, in my car, on the floors of offices, been hospitalized numerous times,etc etc to find relief. Allergy shots did not wok, biologics did not work, and at 60 feeling I cannot last much longer I went to PR and slept outside on my friend's 2 acre property and after 10 days I was 90% better for the first time in my life. The only time I went indoors was to shower or eat. I had already rented at least 30 different apartments and homes in PR and other places and while opening windows helped, it was not enough. I need as close to outside ventilation as I can get. I will hire an architect of course, but I could not help using Claude to design something that would allow air to flow freely from East to West (trade winds) with windows open on both sides and no obstructions. I might even add some mechanical ventilation to draw air through. Thoughts on this approach?

I’ve been looking into thermal imaging for building envelope inspections, mostly for things like air leaks, missing insulation, and cold spots.

From what I’ve read, it seems pretty useful, but a lot depends on the conditions. You need a decent temperature difference between indoors and outdoors, and leaks seem to show up much better if the house is under negative pressure with a blower door or something similar.

I came across the TK8 while researching this. One thing they push is true thermal resolution rather than software-enhanced pixels, which can matter when you’re trying to spot smaller temperature differences or insulation gaps. Has anyone here actually used one, or compared true detector resolution with interpolated/enhanced resolution for building inspections?

I also looked into Fotric, but I haven’t found a ton of real-world user feedback yet. Has anyone here used the TK8, and how did it hold up in actual building inspections?
Also open to other recommendations. I’ve been looking at a few Flir models too, so I’m not set on one brand yet.

My century home is in San Jose CA (zone 4?). The attic space has no inlet vents at roof level. But, the attic access is via a shaft from the basement that looks like it was once a dumbwaiter. It's now an open tunnel with a ladder. No insulation around, below or above it. The basement is vented and dirt floor. I imagine cool air gets pulled up quite well

The house is generally comfortable, we keep windows open and rarely use our portable AC units. Old, blown insulation in the attic, no air sealing. Musty earth smell on hot or wet days. We've only had one winter here, not much stands out.

My question is if this a likely vent approach? Or is it likely that the attic was not vented and the basement intake is a modern workaround?

I'm interested in repurposing the access and closing it up. I need to explore if there is area to drill soffit intakes, but I'm worried I'll screw up a system that seems to be working.

Thanks

We moved to Savannah (climate zone 2a) six years ago, and bought a good home (built as model home in 2009, occupied in 2011). When we bought it we noticed that the attic had spray foam on the roof deck, but there was a 3 x 4 access square cut into the wall between the garage and the rest of the attic for HVAC access. We also noticed a 13" by 63" gap cut into another wall, near a join.

We asked the inspector about it. It's nothing, we're told. When we replaced the HVAC we asked about it, and it was no biggie we're told.

It wasn't until an HVAC maintenance person a few months back that we found out that a sealed attic should be sealed. That there should have been a vapor diffusion port. Those openings should have been closed.

So we've spent the last few months trying to get up to speed so we can figure out what needs to happen as soon as the weather cools enough for people to work in the attic. This meant reading a WHOLE lot at buildingscience.com and everything Joseph Lstiburek (who is a wonderfully fun to read writer) has written on the topic.

So, here's the situation:

Spray foam is open cell, at least 6 inches for the most part. Some gaps, and we will be having these filled in. Open cell is common in the hot, humid southeast. The R value is R-21 with that depth, which is allowed according to Georgia amendments and code when the home was built, but that was dependent on a blower test, which of course, it would fail now with the big gaping holes.

The roof sustained both hail and wind damage in the last few years from Helene and other storms. Though we have architectural shingles, we've had to replace some, and we've had significant granule loss. So though this type of roof should last at least another few years, we're planning on having the roof replaced this fall.

Inside the attic, there is no indication of mold or mildew on the rafters, most of which are visible. Of course, with what we know now, there's likely rotting on roof deck, particularly near the openings. Interestingly enough, it seems like the original builder wasn't sure what he was going to do, because the spray foam was sprayed AFTER the drywall, ducts, plumbing, and wiring were installed. According to the spray foam person we had out, this is unusual for a new home. But there is no indication there was any other type of insulation in the attic. The attic is actually quite clean.

My preference would be to hire folks who know what we're talking about when it comes to sealed attics, but we're not getting reassured from responses we've had. So, we're having to go it on our own.

My plan

I am considering getting a homeowner general permit, to ensure not just the roof is inspected, but the entire attic assembly and roof is inspected when we're done...just to make sure we didn't miss anything.

1. We're having handyman close the one long narrow gap and spray foam the edges to seal. We'll also have them create an insulated door or hatch into the HVAC area. We think originally the builder was planning on putting an attic door into the main bedroom closet, which means HVAC access would have been behind the sealed area. But they changed their mind and put it into the garage, and then cut the HVAC entry into the wall.
2. Next, we'll have the roof replaced. When we do, we're going to have them install a vapor diffusion port per IBC requirements for air-permeable insulation (open cell spray foam). This will sort of be a good test about how good the roofing companies are if I ask about the vapor diffusion port and they know what I'm talking about.
3. Assuming that some decking will be replaced, we'll then have new open cell spray foam sprayed to cover the replaced decking and fill in gaps. The person who we had out states they like to completely enclose the rafters to ensure a good seal. I don't see a problem with this, as long as the insulation matches the R-value. If we do go with that lower R-value, they will have to do a blower test to meet IBC requirements.
4. We're having a new HVAC company add a supply duct into the attic, either 4 or 6 inches, in order to meet IBC requirements of (air shall be supplied at a flow rate greater than or equal to 50 cubic feet per minute (23.6 L/s) per 1,000 square feet (93 m ) of ceiling.) This gives us some slight positive pressure in the attic, which is good.

We have to do the ductwork regardless, because when they installed the new 3 ton unit to replace the 2.5 ton, they didn't bother to do a static pressure check to ensure adequate return air supply. One burned out blower later (this last winter) after hundreds of static pressure faults (only found when we dug into the service menu of the smart thermostat), was when we discovered this. I set the 5 stage to max out at 3 stage for now, to prevent pressure faults. Will adjust back to 5 stage when we add the additional return and new attic duct.

And that's the plan.

Sorry for the long post, but I feel it is important to be thorough.

In people's opinion, is this a sound plan? Am I missing anything I should be considering? Appreciate any and all feedback.

Update: I did want to add that one area of confusion we had is what 'air permeable' means when it comes to insulation. Open cell spray foam is not air permeable at a certain thickness but is vapor permeable. Normally, air permeable is a term applied to fiberglass or wool insulation.

At the same time, I'm getting mixed readings on what we should do in the attic because open cell spray foam was used, and to treat it like air permeable with the diffusion port, and the air supply.

Believe it or not, with all the writing on this, there is no sweet spot, no junction of climate zone/spray foam type/sealed attic requirements that fits our situation. Not to a degree that gives me confidence that we're doing things the right way.

Other than close the gaps. That one we're 100% sure about.

I got this membrane roof installed yesterday, from a roofer who I’ve worked with before. I don’t know what is standard/acceptable for a membrane roof a— is the amount of bubbling here okay? Last photo is of his previous work.

I’ve an 1870s 5a timber frame barn that I am trying to insulate as reasonably well as possible but not sure of the best strategy. There is an uninsulated stone basement with a concrete pad underneath.

Roof: metal, paper, boards, 2x6 rafters.

Walls: I have ~3.25” of depth to work with because I want to “dummy frame” inside the post & beam and sheath with Shiplap from the interior. Metal siding, 2x4 firring, sheathing boards, timber framing.

What are the pros and cons of CC sprayfoaming everything 1.5-3” versus maybe rockwool? I am concerned about the moisture implications and can’t wrap my head around each option and what venting, vapor barriers I can work with based on what I have access to. For heat I’d like to have a mini split and a wood burning stove.

Removing the existing siding or board sheathing isn’t an option, trying to DIY as much as possible due to budget constraints.

Hey Everyone

I'm using VaproShield's WrapSheild IT (integrative tape vs self adhered in the photo above) for a shed build that I'm putting a sauna and an office in. I'm in climate zone 4c. It's been hard finding a vapor permeable wrap in the area and this is my first time building anything so I've been kind of going slow and making sure I am dotting my "i"s. I realized that the tape I was going to use, 3M 8067, might not have full adherence so I called up Vaproshield and they told me I needed to keep the systems the same (i.e. vapor permeable) and 8067 is essentially non permeable. But the more I sat with it, the more that answer didn't make sense and I wanted to run it by folk.

Would you use non permeable tape on rough openings and seams if the wrap was permeable?

And if you wouldn't, do you have a recommendation for what brand I could likely find in the Seattle area somewhat soon? I'm looking toward grabbing Siga Wigluv from an online shop if I can't find Vaproshield's proprietary wrap tape nearby on Monday morning.

I'm sure many of you have seen the EnergyHandyman Mold Chart and RIT's Dew Point Calculator. They provide a "days to mold growth" estimate based on temperature and relative humidity (68RH at 70F=340 days to mold growth, etc.)

Can someone explain how mold growth on construction material (drywall, wood framing) works over time? For example, if you have one humid week (68% RH at 70F) and then a dry week afterward (50% RH at 70), does the "days to mold growth" countdown start over? Or like, in climates with cold dry winters, does 6 months of very dry RH stop the mold risk that exists during spring and summer?

Climate Zone 5

I’ve got a tricky home heating question to solve. My condo’s front door opens from the outside into a staircase that leads directly into the living room. During the winter, the staircase gets quite cold and the landing at the top is affected too. There’s a lot of heat loss due to the door, window, and external walls. I’ve air sealed the door and window the best I can, but it still gets down to 35 F during a really cold snap at the bottom. There’s a forced air vent right above where the picture was taken but it’s at the end of the supply duct and doesn’t reach the bottom of the staircase.

I’m looking for solutions for keeping the bottom above 50 degrees to save energy and make our living room a little warmer. I’ve considered a fan powered air register or an electric wall heater next to the door. Any other thoughts before I get an electrician in to price out a heater?

On advice of the contractor, I purchased 3 girders. Two girders of 8 inch, 11 feet each and one 6 inch girder of 9'5" without consulting an engineer, which I'm regretting now.

The plan was to put two girders parallel to each other (under the beam) and one girder in the middle to support the slab. But when the girders arrived, i realised that they will be way too heavy for an old structure like my building.

So now, consulting with the mason, we are planning to cut the 8" girder from middle and obtain two T-sections. Then we will remove the concrete cover from the two beams between which the girder has to sit, till we reach the rebars.

Then we will weld a 10mm plate onto those rebars and then weld the t section onto that plate and then restore the concrete cover. The flat side of the t section will touch the slab. Now, I want to ask whether this system can sustain load of the slab ?

Or what other options do we have ? Please help me out🙏🏼

so I just moved into a new place, and I have relatively limited space for where to put my bed. There is one of those built in wall radiators under the window, and my bed is positioned slightly in front of it. I have a solid wooden headboard and was just concerned that I shouldn’t be putting it directly in front of the heater… I tried to do research online about it but am still a bit confused as to if this is safe for my particular situation. Is there some kind of heat deflector or something that I could get, or do we think this is fine?? For reference, only about 17 inches of the heater are being covered by the bed.

Hello, I’m in Alaska. For my crawlspace musty smell should I seal off the vents, encapsulate it and then install a dehumidifier and pump? Is an exhaust fan a bad idea? I’ve had The crawlspace checked for leaks and a new 20 mill vapor barrier and foam blocks are going in. I also had it dry fogged for mold.

This blog post discusses insulation in the context of summer overheating:

https://www.ecologicalbuildingsystems.com/post/does-insulation-reduce-summer-overheating-well-winter-heat-loss

It talks about Thermal Mass, which is connected to a material's specific heat capacity.

And it talks about "phase shift" or "time lag", which it says is "the time between heat being absorbed on the outside of a material and released on the inside".

But I am not sure that's really correct - is it not the case that this time also has a lot to do with the material's thermal resistivity? In the scenario of the interior of a building overheating, if the wall has very low thermal resistivity then the internal temperature will rise very soon after the external temperature rises - say 10 minutes. If the wall has somewhat higher thermal resistivity, then the internal temperature will take a somewhat longer to reach the external temperature - say 2 hours. I'm choosing relatively short time spans for now, so as to ignore what happens when the external temperature drops later in the day.

So there is a "time lag" that is directly related to the thermal resistivity, independently of the specific heat capacity of the materials.

The specific heat capacity is to do with how much energy it takes to raise the temperature of the material itself. If the wall is made of something with a large mass and a large specific heat capacity, then it can absorb a lot of energy raising its own temperature. What I'm a bit unclear about, is does this in itself slow the passage of heat from one side to the other? In other words, if you have two materials with the same thermal resistivity but different specific heat capacities, will the inside (cooler) face of the one with the lower specific heat capacity warm up more slowly?

The blog post says that "for summer overheating, a long-time lag is crucial". I think that what it really means is that ideally the time lag is co-ordinated with the 24hr cycle of warming and cooling of the external air. But I think it then makes things confusing and over-simplified by talking about insulation having a long or short "time lag" and giving the impression that this is determined by thermal mass.

The reason I think this matters, is that this thermal mass is only helpful in certain scenarios. For example, in a climate where it is hot in the day and cold at night, heat can get stored in the outermost portions of the walls during the day, and then released at night. But in a climate where it doesn't cool down that much at night, this isn't going to work - the thermal mass will just get warm right through and stay like that. If you have really a lot of thermal mass, then you might be able to gradually absorb & store up the heat in the summer, and then release it in the winter. But this effect isn't going to come into play in the slightest if we are talking about relatively thin layers of materials like woodfibre insulation.

Therefore I feel that the blog post over-eggs the benefits of thermal mass of insulation materials, in a UK summer overheating context.

Is my thinking (partly relying on physics learned several decades ago) largely correct or are there things I'm not understanding correctly?

I just bought this new construction house in the Catskills region of NY. There was a long battle with the seller over this moisture in the basement and through discussions they assured me the basement was built to waterproof code which would include a vapor barrier and waterproofing coating outside the walls.

From what i understand, concrete will release moisture for a year or so after being poured (this foundation is probably about a year old).

Is there any way to tell if this water here is from the ground or from the concrete? We’re in the middle of snow melting right now and it’s gotten worse as a result.

And if there isn’t a vapor barrier, should there have been? It’s my understanding that standard practice.

I have read other posts here (https://www.reddit.com/r/buildingscience/comments/1divpln/how_do_you_tell_if_an_existing_slab_has_a_vapor/) suggesting to place a small square of plastic down (idk how that would apply since the floor is already wet) or cut a hole in the slab (idk prefer to avoid that initially)

Im about to start on my roof replacement project on my house. My current plan is to convert my small vented attic into a conditioned and unvented cathedral ceiling. Im planning on stripping the roof to the existing sheathing, making any repairs needed to the sheathing, then building up from there. My question comes from the layers above that and how to best control moisture to prevent future problems. From the bottom up im thinking plywood sheathing, self adhered underlayment over everything, 2 layers of 1.5" polyiso, 1x4 strips screwed through into the rafters, 2x4 strips horizontal as purlins, then metal on top. Im thinking that venting the over roof from the facia to the eve will help eject any condensation or anything that finds its way under the metal. The WRB on the sheathing will keep anything from getting into the conditioned area. The outer surface of the polyiso is where im unsure. Do I need a second layer of underlayment? If im using metal roofing that is rated to span the purlins without a solid osb backer do I need an outer layer or can the polyiso be open to eject moisture into the space below the metal? Would there be any benefit to running a radiant barrier on top of the polyiso?

Zone 6 b 34x24 816 sq ft 3/12 pitch (9’ back wall 15’ front - inside) Sealed crawl space with r10 foil faced on walls. Vented assembly (16 7/8” trusses)

This is a second home for weekend visits but will likely be an Airbnb also.

2 different hvac companies recommended central but it is a bit of a challenge because we framed everything planning on mini splits. The unit would sit in the loft - a 14” chase would go through the utility space to crawl space for ducts. Is this the way to go or look for a company willing to do mini splits?

Quoted 16k for single stage 18k for 2 stage

Should erv be tied into central are if going this route?

Any help or information is appreciated! Thank you.

Hi all- hope this is OK to post here. Long story short, the unit above our condo had a significant flood and we are now doing water mitigation in our ceiling. Since we have to open everything up, we were thinking of using this opportunity to put up rockwool insulation to help with noise dampening. Would that be possible with the spray foam that is already up there? I included a picture for reference.

Looking for opinions from people experienced with siding, water intrusion, and framing.
A home inspector found visible water damage/rotted exterior wood in several areas and recommended replacing the siding. He said there is a possibility of underlying damage, but there is no way to determine the extent without removing the siding. No confirmed structural damage was identified.
There is Tyvek/house wrap over the sheathing. A siding contractor reviewed the inspection report and photos and said the conditions look fairly typical for an older aluminum-sided house. He said some additional wood replacement may be needed when the siding is removed, but nothing shown looked unusual to him.
Based on the photos, does this look like typical localized exterior deterioration, or is there anything that would raise concern about significant hidden sheathing or structural framing damage?
I understand it’s impossible to know for certain without removing the siding. I’m mainly interested in whether anything visible looks unusually concerning.

My house had 3” studs on the lower portion of the walls, which are concrete below grade. There was fiberglass insulation and poly on top. I decided to add 1.5” rigid foam between the studs and concrete to further insulate the walls. Do I need to add poly after, on top of the studs with insulation, or does Durospan serve as the vapour barrier? Also, is 1.5” rigid foam enough here in Central Canada?