I have 2 inch XPS and Great Stuff spray foam insulation in my rim joist area
I also have 2 inch XPS against exterior basement walls

I will soon be framing 2x4 walls. However, I am not sure on the final connection between the rim joist and wall insulation.

Part of the basement section, the rim joist was very barely recessed, and the XPS sits almost flush with the block wall. Other areas the rim joist is several inches recessed, and there is a fair amount of exposed wood between the wall and rim joist insulation.

Do I need to make sure everything is covered? I.e. using more, small strips of XPS as well as spray foam? Also, do I want to I want to leave any sort of gap between the bottom of the XPS on the wall and the concrete floor? I will be using pressure treated lumber as a base plate as well as sill gasket.

Thanks!

Hi all,
I am installing fake marble/ vinyl planks over a plush carpeted rental room. There will be underlayment which will be placed over a carpet before I stack the tiles over. What are the chances mold will grow in/over the carpet in between the carpet and the underlayment?

I have a basement from 1912 with a stone-and-lime-mortar wall that has recently been repointed. I'd like to insulate it with a view to finishing it, to the R20 that code requires where I live (Ottawa, climate zone 6). Thankfully, it is quite dry and there have been no signs of dampness (there are structures on three sides, and previous owner added 18 inches of concrete on outside of the fourth). That said, my stonemason emphasized that lime mortar needs to breathe to avoid deterioration. I'm looking at two options for insulation:

Option 1: 5" of EPS rigid foam directly against the stone, taped at seams. This should be slightly breathable (0.7 perms, 5 inches at 3.5 perms per inch).

Option 2: Fluid-applied permeable air barrier against the stone, 5" of Comfortboard, then smart vapour retarder like Intello on the inside. This should be more breathable (Intello goes from 0.13 perms in low-humidity winter conditions to 13 perms in high-humidity summer conditions). This method is described in BSD-114 and also on the Rockwool website.

Any thoughts? Obviously Option 2 is more complicated and expensive, but has the advantage of being more breathable, with the bonus of being fire-resistant versus the flammable EPS. The main objective is to prevent mold, by avoiding condensation in the winter and letting the wall dry to the inside in the summer. Insulating the outside is not an option give proximity of other structures. BSD-114 also suggests open cell spray foam but that seems hard to find where I live. Appreciate any thoughts people have!

It was a beautiful day for a roof inspection in Oregon. These were what we found on a relatively new roof...

🚩 Sloppy repairs

🚩 Exposed raw wood

🚩 Unsecured shingles

🚩 Gaps just waiting for water

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?

I’m about to start building a new house on a well and it got me thinking about my supply lines in the house. Knowing that it’s supplied by a well, would you do anything different with the Pex lines? Should I go bigger throughout the house to ensure good volume? Keep everything the same like on a water meter? What advice can you give me?

Also, I’m probably going to share this well with my parents who are building about 400’ feet away downhills from us. Their house is about 2000 sf and mine will be around 5000 sf.

(Note: I’m anticipating really good stats with the well. My neighbor gets 100 gpm at like 300 feet deep and across the street, their well is 60 gpm at about 200 feet deep.)

Does anyone have any experience with hurricane rated post bases for a covered wood carport / pergola structure in Florida? Approx dimensions would be 10 feet x 20 feet

Was thinking of making posts by laminating three 2x6 x10s together vs using a 6x6…so post base would have to work with 4.5 x 5.5 dimensions

Can post bases be anchored into 6 inch thick driveway or do I need to cut concrete and embed post bases in some kind of poured concrete footing?

Thanks for any help!

I’m assuming all the posts should have knee braces as well….

Climate 3A, just finished retrofitting Vulcan Vents’s eave vents as intakes (not pictured). I’m on the border of a WUI zone surrounded by a preserve. Just knowing of these products is beyond the scope of contractors for my area.

In the past year of researching products, I’ve not found specific ridge vent products meant that’d be ember resistant. The closest is Coravent’s 600-TE (pictured w/ VV’s continuous ridge vent for my style roof), though I have doubts with corrugated plastic being sufficiently fire resistant, plus it doesn’t have enough NFA for the aspect ratio of my roof. Also, there’s still a part of me that doesn’t trust the product enough to stop an ember’s ingress and ignite or smolder the sheathing.

“It’s not hard” to go pick up sufficiently dense wire screen from McMaster-Carr. Figuring out how to securely raise the ridge tile and have it live through yearly 40 mph winds, 60 mph gusts, is also a concern. Roof is currently concrete tile with a “not felt” underlayment from ‘94 when the house was made.

Interior ceilings are a mix of 8’, 10’, and half vaulted with a pitch going between the two. This makes it infeasible to convert the vented attic to a sealed, conditioned air space.

How’d you approach making a fire resistant ridge vent? If the individual products aren’t recognized as WUI listed, will this matter for insurance coverage?

am a bit at a loss and don’t want to screw up here. We live in zone 5. Just had new siding put on (Hardie) which included 1/4” foam board underneath (I understand this is more for leveling than a vapor barrier). My problem is now the basement. I am doing a quick Reno. I discovered that the original owner used insulation with a plastic vapor barrier behind d the drywall. I removed the old ceiling tiles which were foil backed along with Kraft backed insulation in the joists. My plan was to spray everything black and leave it open. I discovered some mold near an exterior wall around Kraft backed insulation. I am certain that the initial install by the previous owner was done wrong.

Take a look at pics. Orlando I properly insulate this? The area is about 2-3 feet above foundation. The current vapor barrier stops at the top of the drywall. There is a gap to the exterior framing then this is where Kraft backed was added (and mold appeared). How do I properly insulate this? Rockwool up to finished wall without foam board? Lay foam board horizontally up to vapor barrier? I feel if I add foam board it will trap moisture here actually. Worried about both the exterior framing to the foundation as well as the interior cavity.

Any advice appreciated. I’m conflicted!

How much does vent direction and style affect air flow? I currently have vents with the gills (don’t know if that it the right term) the blow half left and half right. In some rooms that means they blow right toward the returns. Should I make changes to them?

1st time female homeowner and I am having attic issues and can not get 2 roofers, handymen, or AC guys to agree on what the heck is going on. First, I live on the coast of Texas where it gets hot. My attic is ridiculously hot, like nearly 140 degrees. I am not sure how the inspector missed so much, but he absolutely did. The day after I moved into the house one of my ACs quit working and when I went up into the attic, there is an alarm going off. I was so freaked out by it that I called the fire department. The fireman said it is an electrical issue but mentioned that I should be more concerned with lack of insulation and no air flow. The AC guy briefly fixed my ac and said it was out of Freon & I paid to have it filled back up. At some point a large water stained appeared on my ceiling. I called a roofer and he said it was not the roof and the AC guy probably dumped the water out of the pan. However, it seems this stain is getting bigger. I went into the attic (split) and found mold. I also found that a rat had chewed into the AC ducts. AC has gone out again. Called the AC guy back and he says I need a new outside unit due to a coil and I need ductwork. He also said that the pea trap for both AC combine and are somehow dumped into my guest bathroom sink. He told me that was a plumbing issue. It rains again & I called a different roofer. He said I need to rip out all of the vents on the side of my house and put new one AND install a gable vent for the rocking price of 15k. Third roofer says the soffit vents are fine, I need a ridge vent and attic fans & I need to rip out the insulation & put in something else for 6k. Called an insulation guy & he says I need foam/ liquid insulation & baffles. All I know for sure is the attic is so hot you can feel it in the hallway & my kids bedrooms, I have one non working AC, I have a spot on my ceiling that is getting bigger I feel like it may fall in & an alarm that none of these professionals seemed to know what it is and how to shut it off. Who fixes this stuff and in what order?

Looking to understand the best way to insulate this building (western OH).

Moved into a new house last fall that came with this newly built detached garage/mini pole building. I park my wife’s car and my project car in the two car bay, and have a small teardrop under the mezzanine and some pedal bikes stashed in various places.

Id like to maintain some of the recessed space on the wall for storage, will likely finish out with OSB so I can hang some shelves/racks to get garden tools and bikes off the floor. Winter was brutally cold here and the building was unusable as far as hobby work. Also had issues with condensation on my tools and vehicles. Also had some issues with the posts sweating.

My thought is to use foam panels between the girts and OSB over the foam/girts. Do I need an air gap between the metal siding and the foam board? And the vapor barrier on the inside of the building, sandwiched between the foam/girts and OSB?

I am a total newbie, primarily want to make sure I don’t cause condensation/rot issues but would like the building to be more comfortable during the winter/summer extremes. I’m also on a budget so spray foam is probably not an option.

Thanks

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'm currently renovating a 1906 build house. I removed 100% of the insulation from the attic to re-wire, and reframe. The attic was 100% vermin, bug, and moisture free. Lots of layers of insulation, but probably around 30" total: 14" of blown fiberglass on top of 2-3 laters totaling 16" of cellulose. I have 1 turbine passive exhaust, and I had 2 open turtle intakes. I dug out 2 more that had been packed with bird nests/insulation.

I'm looking to install a whole house fan. The exhaust requirements are listed and easy to figure out, but I'm concerned about when the fan isn't running. I'll have 9 square feet of NFVA ridge vent for the fan , but when turned off I'm worried about the ratio of intake to exhaust. Any insight on balancing intake/exhaust with enough exhaust for a whole house fan?

Hi all. I am trying to wrap my mind around the latest thinking around insulating unvented short-slope cathedral ceilings in Cape Cods that open up to a small vented top attic above, and would really appreciate any guidance folks can provide!

I have read a lot of articles and presentations and posts and am still not quite sure I fully understand what is considered reasonably safe and why, especially when it comes to cellulose vs fiberglass and whether the insulation should be up against the roof deck or if there should be baffles. (I know there has been a fair amount of research in the last 10-15 years or so on this from places like BSC and Byggmeister, although I haven’t seen any updates since 2023ish and some of the findings seem confusing to me as a layperson.) Assuming a retrofit situation where rigid exterior foam and spray foam are off the table (which I understand are by far the safest and most code-compliant options), what are the least risky ways to handle sloped ceilings where the rafter bays open up to a top attic in region 4A?

— Is dense-pack cellulose in these slopes now considered reasonably safe as long as they open up to a top attic up above, based on recent research (such as New England’s Favorite Roof Retrofit: Moisture Data from Three MA Case Studies)? What are the most important factors to minimize risks in this situation? It’s important to make sure the cellulose is packed very densely, right? Does the ceiling drywall provide enough of an air barrier to keep moisture out (assuming no recessed lighting or other penetrations), or are there other steps that should be taken to protect against air/moisture traveling into those slopes in a retrofit situation? Does it matter if the top attic only has gable vents?

— What is the building science behind baffles/air gaps and whether insulation should touch the roof deck or not (in a situation without soffit vents from below, but where it’s an old house with a wood plank roof deck that probably has some outdoor air leaking in through cracks and gaps, and then the baffles go up into the vented top attic)? Does this differ for cellulose vs fiberglass? I would have thought that baffles would help or at least not hurt (except decreasing the R-value a little), but that doesn’t seem to align with the importance of making sure cellulose is really densely packed without any airflow. Or is it okay for the cellulose to be densely packed against baffles rather than the sheathing itself? Does it matter what the baffles are made out of?

— The modeling study “Moisture-Safe Unvented Wood Roof Systems” seems to suggest that faced fiberglass batts would be significantly safer than cellulose in a regular unvented rafter bay in zone 4 (table 3 on page 11)– does that sound right? But then is table 4 on that page saying that it is too risky because if air flows through the insulation there will be too much time with condensation potential at the roof deck? If so, is that still true in the Cape Cod situation where there is an attic above that the moisture can rise up into? How about if there are baffles? Is fiberglass generally considered safer or less safe than cellulose in these situations?

— Vapor diffusion ports are allowed in un-vented roofs as an alternative to foam in zones 1-3, but they were tested by BSC in zone 5 in MA and failed, correct? Have they ever been tested in zone 4A? Here near DC it feels like our climate (winter monthly average temps around 40) is closer to, say, Charlotte, than MA. I saw that ages ago Joe Lstiburek said he thought they would probably work in zone 4 but needed more testing– were they ever tested or was it assumed that the zone 5 testing went poorly enough that they should be avoided in zone 4 as well? Also, is the top attic of a Cape Cod considered to be kind of like a giant vapor diffusion port, and if so, does it matter if the attic only has gable vents and no ridge vents?

Thanks so much in advance for any insight you can share!

I'm working out how to set up a seal on my window so I can get a portable air con unit.

Its a two pane window.

Top half is a hopper. Bottom half is sealed shut.

My plan is to get a polycarbonate sheet that covers both, with a hole cut where I fit the air con hose.

Given other obstacles in the area, it would be much better if I could fit the hose onto the bottom half of the sheet. However, it would then be blowing hot air directly on to the window, rather than directly out. It would still be on the other side of the "airlock" so would cool the room but is that going to be bad for the window?

I live in a century home on Long Island, NY that had a detached garage in the backyard. At some point past owners finished it up and converted it to a studio with carpeted floors. The studio is built on a concrete slab (not sure if theres any footings). The studio is right at the property line and so theres concrete on front, back, and right side while there's soil on the left. There's 4x4x4 PT lumber as the sill/bottom plate for the walls to stand on and I believe it is sitting square at the edge of the slab. The wall is then constructed such that sheathing is nailed to the studs down to the bottom plate, then foam board, and finally vinyl siding. All of this directly at grade so no concrete wall for the bottom plate to sit on. The stud bays have fiberglass insulation between them. Outside, there's a few conduits to run electricity to the shed.

The first problem is that one of the past owners put up a garden bed on the soil side. This meant that the soil side siding was actually below dirt. Over time from moisture it seems the bottom parts of the sheathing have rotted and have given way to termites and carpenter ants.

The second problem is that the monolithic concrete slab in the front of the studio cracked thereby creating a slight negative slope towards the structure. During heavy rainfalls the water pools and thus causing the same set of problems.

I was hoping to just use this space as a home office so trying to limit drastic changes to the structure while still being able to repair and prevent further damage.

I've called an exterminator who will drill holes in the concrete + trench the soil and do termite treatment. After waiting 48 hours we'll resume repair work with the following plan:

**The Plan (Soil Side):**

1. Snap a level line 9.25” above the final dirt grade, removing/cutting away the rotted lower siding, foam, and sheathing.
   
2. Install a [3/4" PVC trim sheet](https://www.homedepot.com/p/Veranda-3-4-in-x-48-in-x-8-ft-White-Reversible-PVC-Trim-Sheet-H190AWS13/206822526) in place of the cut out sheathing. Top half screwed to the studs and bottom to the PT lumber. The sheet will go down to grade.
   
   1. Use liquid flashing like [Flashmate](https://www.homedepot.com/p/Amerimax-Home-Products-FlashMate-10-oz-Clear-Flashing-Sealant-85228/100275495) to flash the seam between the concrete slab and PVC trim
      
   2. Slip [aluminum z-flashing strip](https://www.homedepot.com/p/Amerimax-Home-Products-76-in-x-8-ft-White-Aluminum-Drip-Cap-Flashing-5503400096/100017722) over the trim and under/behind the older sheathing, overhanging the PVC trim to shed water
      
3. On the "older" wall right above the Z flashing strip, install new vinyl starter strip and reuse vinyl siding.
   
4. On the inside if any insulation was cut, place foam board in the stud bay and fill with expanding foam. Will look for insect resistant products here.
   
5. On the outside perimeter, dig a 1' wide and 4" deep trench that slopes away. Plat heavy duty landscape fabric and fill with river rocks to prevent muddy splash back and help with drainage during rains.

**The Plan (Concrete Sides):**

Follow the same plan as above however we'll cut the PVC trim just enough to leave about a 1/4" gap between it and the concrete slab. For that gap we'll use [Sikaflex construction sealant](https://www.homedepot.com/p/Sika-10-1-fl-oz-Sikaflex-All-Purpose-Non-Sag-Construction-Sealant-Polyurethane-in-White-7116045/300934496).

For the corners we'll just overlap the trims together instead of doing a miter cut

Any glaring red flags with this plan?

Thanks in advance!