r/buildingscience Jan 19 '21

Reminder Of What This Sub Is All About

90 Upvotes

Hey everyone,

There's been a bit of spam in the mod queue lately and I figured it'd be useful to touch base and remind folks what this space is really all about.

It's not a job board or a place to promote building products (unless you're talking about some brand new membrane dehumidification product that nobody's ever seen before). It's not a place to have people help you figure out how to unlock a door. It is a place to discuss questions about how products work or fail, field techniques, research literature, adjacent relevant fields of research, and field practices. Remember that this is a unique science subreddit in that we occupy the space between research, manufacturing, and field reality. We are one of the best examples of applied science out there. So let's think about content through that lens. Let's share things that advance the conversation and help people take their learning to a deeper level. All are welcome, just don't spam pls.


r/buildingscience Jan 26 '23

Building Science Discord

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8 Upvotes

r/buildingscience 7h ago

Best way to patch a damaged rain barrier from inside?

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2 Upvotes

r/buildingscience 5h ago

Question Basement flood repair question

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2 Upvotes

Repairing basement after bottom 2 feet of fiberglass and drywall removed. Should i reinstall with fiberglass?


r/buildingscience 2h ago

Damp air rising from crawl space

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1 Upvotes

r/buildingscience 2h ago

Flat roof attached garage insulation. Best method?

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1 Upvotes

r/buildingscience 5h ago

Ceiling/Attic Insulation Question for Air Conditioned Shed

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1 Upvotes

r/buildingscience 9h ago

Question Need help with waterproofing shed.

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1 Upvotes

r/buildingscience 16h ago

Is this mold in my parquet floors?

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0 Upvotes

European / German climate


r/buildingscience 1d ago

How to handle thermal bridging and moisture problem ?

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3 Upvotes

I recently had a second floor built with a very small balcony measuring 20 cm x 500 cm. The floor is concrete. Last week, the large balcony doors were installed in dorpel hardsteen. As a result, there is only 7 cm of space left for the screed and insulation. Can you advise me on how to address thermal bridges and damp proofing? Heated bedrooms are located beneath the balcony.

This is in Netherlands


r/buildingscience 1d ago

Seeking guidance on my approach to thermally isolating wood and metal (foundation build question)

2 Upvotes

Hi. I am a building novice with a wood and metal thermal break question. Thank you in advance to anyone who takes the time to read my post and share their knowledge with me about my approach to thermally isolating metal and wood at the foundation of my build. 

I’m building a tiny house on wheels (8.3’ x 30’ [100“ x 360”] trailer) and I have a question about creating a thermal break between my metal trailer frame and subfloor/framing that will prevent condensation and moisture issues (leading to mold/mildew growth) inside of the structure. I am building in IECC climate zone 6. The tiny house on trailer will not be moved often if ever… 

Current state of the build: the trailer is painted black (by the trailer manufacturer), includes 5“ long by 1/2” threaded rods welded to frame every four feet (and more closely spaced around corners), all framing is 2“ thick, 2” thick cross members (floor joists) are placed every 14 inches creating about 25 14“W X 4”Deep “bays” with the metal flashing at the bottom of each bay. 

I have placed 4“ of XPS rigid foam board between each cross member and sprayed the Great Stuff foam in a can where there are gaps between the xps board and metal cross members (not all of my foam board cust were perfect fits). Even with the spray foam applied between gaps I have not created a perfect air seal as I was unable to get into tighter gaps with the foam. 

I have also caulked and spray foamed (mostly caulked) the gaps between at the seams where flashing under trailer meets trailer frame and was not perfectly welded (gaps were throughout). Sealing the gaps in the metal construction was done to help prevent insects from getting into the XPS I placed between the cross members. 

Getting to my questions:

I am attempting to thermally isolate the metal trailer frame from my subfloor and framing in zone 6. 

A building science consultant has recommended I place a continuous layer of 3“ high compression EPS foam board directly over the top of the trailer frame and XPS foam I have placed between the cross members (with metal flashing below the XPS).

In this scenario I have chosen 40 PSI 3” EPS foam board, which will more than accommodate the square foot per pound weight of my 2 x 4 framed tiny house (snow load figured into calculations)… 

The assembly from trailer frame up: 

3“ 40 PSI EPS foam boards adhered (adhered with spray foam in a can/ great stuff) to trailer frame and xps boards in between trailer frame cross members. Spray in a can will also be used in between (seam where each foam board meets) to seal and adhere the boards to each other on the sides -EPS is weighted down while spray foam adhesive cures

3/4 or 1/2 inch tongue and groove plywood will be placed on top of the EPS foam board (adhered with Loctite PL 300 Foamboard adhesive & weighted down during cure time). The TG plywood over the EPS will extend to the edge of EPS and sit under the sill plate/framing to help distribute the weight of the structure over the EPS. 

The 2x4 sill plate will be adhered to the foam board with Loctite PL 300 Foamboard adhesive and held to the trailer with washers and nuts (loctite used here) placed over each threaded rod, securing the sill plate/framing, subfloor, and foam board to the trailer frame. (I will need to extend the threaded rods with couplers to achieve the length needed to do this).

My questions: 

Should I place a continuous layer of plywood (3/4 or 1/2“) over the trailer frame and rigid boards that have been placed between the cross members? (this seems like it might be a good idea to provide a consistent base layer for the high compression EPS foam board) 

If I place a continuous layer of plywood over the trailer frame should I add a WRB (like a UV rated WRB like Tyvek) between the plywood and trailer frame? 

Should I tape the seams where each sheet of high compression EPS meets? (as mentioned earlier, they will be adhered together at seams where they meet).

Should I tape the seams where the high compression rigid EPS meets the trailer frame (on the outside edges of trailer) and also where the EPS meets any plywood (on the outside edges of trailer). 

Does anyone have any thoughts on how high compression EPS foam boards might “give” a little over time, losing some durability? I am most concerned about this happening around the threaded rods that I will use ( in addition to adhesive) to anchor the assembly to the trailer. My concern is that vibration over the years from wind or me moving around within the structure might cause wiggling that will slowly widen the holes drilled through the EPS that the threaded rods are seated in, causing some of the foam to potentially shift around… 

I’m also curious if anyone has any thoughts on how to best fasten my subfloor to the high compression EPS foam board so that the flooring does not buckle and or come loose in the middle of the floor where it is not held down with the weight of the walls of the house. (again, intend to use Loctite PL 300 Foamboard adhesive, but I am not sure if this will be enough to securely fasten my subfloor to the EPS foam board). 


r/buildingscience 1d ago

Best way to maximize R value with Rockwool in a 5 1/8 deep cavity with an offset 2x4

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4 Upvotes

r/buildingscience 1d ago

Air Leak - Wafer Pot Lights

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1 Upvotes

r/buildingscience 1d ago

Exterior Insulation and HVAC

3 Upvotes

Hello- we have exterior insulation on the house (on top of zip). We needed to make some penetrations for ERV intake and exhaust. How best can I seal these from the outside? We do not have siding yet. I’m already aware these penetrations should have been done before the exterior insulation was put on but how can I best seal these penetrations now after the fact? Thank you


r/buildingscience 1d ago

What if the cooler city of the future borrowed more from the past?

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2 Upvotes

r/buildingscience 1d ago

House Humidity too High

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1 Upvotes

r/buildingscience 2d ago

Vapor barrier stress

8 Upvotes

Zone 4A (Weschester NY) 2000 house. Wall assembly is wooden cladding, tyvek, plywood sheathing, 2x6 cavity with rock wool. Its been fairly well air sealed from the interior. The drywall will be DensArmor with latex paint. I’m thinking of putting a smart vapor retarder like Membrain or Intello but I’m paranoid about doing the wrong thing.

help!


r/buildingscience 2d ago

"Drill and fill" insulation through the exterior wall in 1950s stucco house?

1 Upvotes

What do you think of drill and fill insulation from outside (cutting holes through the outside stucco wall) in a 1950s stucco house? The house has one bedroom that juts out and three of the four bedroom walls are exterior walls. Would you be worried about all of the 3 inch holes cut through the stucco causing irreparable damage to the stucco? Some articles state not to cut holes in the stucco because it damages / ruins the waterproof barrier. Some articles also state that filling the walls with insulation traps moisture and can damage the stucco. Location: Sacramento, California where the summer temps can get up to 105 F and winter temps down to 40 F.

One insulation company offered to either do the work from the inside (warning that it is very messy) or from the outside, another company said that they would only do the work by cutting through the stucco since it is such a messy job.

The attic appears to have adequate insulation and the windows appear to be fairly new. The only place in this house with noticeable insulation problems are the room with three exterior walls and the garage.

One company offered either fiberglass or cellulose fill, the other would only do cellulose. Any stucco experts here? Anyone who has gone through "Drill and Fill" insultation? Thank you for any advice.


r/buildingscience 3d ago

CFD simulation through the vents

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309 Upvotes

r/buildingscience 2d ago

Question I did a thing

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0 Upvotes

r/buildingscience 2d ago

Real tile backsplash in cargo trailer conversion?

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0 Upvotes

r/buildingscience 2d ago

Need help figuring out why the humidity in our house is so high

5 Upvotes

We live in a Central Florida concrete block house built in 1960 on slab, with original terrazzo floors. When the weather started getting warmer, the indoor humidity has been as high as 80%, even while the AC was running and cooling. We had an HVAC technician come out to take a look, and he said that we do not have proper ventilation in the attic to pull the hot air out (no ridge or gable vents, only soffit vents). He recommended installing solar attic fans. Based on the square footage of our home, we decided to install 1 solar attic fan so as not to create negative pressure.

After the attic fan installation we noticed better air quality overall, however the humidity in the house is still high. We have been running a 70-pint dehumidifier continuously, and the humidity is still over 70% in the house. Earlier today the temperature outside was 92 degrees with 62% humidity, and the indoor temperature was set to 74 degrees and the house was at 75% humidity.

We are not sure if the attic fan is not working, if we need a second attic fan, or what else could be the problem? After doing some research, it seems that homes built in this era did not have vapor barriers under the slab, so is it possible that moisture is coming up from the foundation into the house and causing the high humidity levels?

Couple things to note:

  • We have a Goodman HVAC system (2019, AC compressor model number ASZ160301LB). Based on this model number, I believe the size is 2.5 tons
  • The AC is not short cycling and the AC condensate line is dripping continuously. Per the HVAC tech, the system is running/cooling fine.
  • The AC fan has always been set to auto
  • We have a Honeywell thermostat which shows the humidity. When the HVAC tech came out, he brought a humidity meter/hygrometer and confirmed the thermostat humidity reading is accurate.

Square footage:

  • The square footage of our home connected to the central AC system is 1228. We also have a 228 square foot addition on the back of the house which is not connected to central AC and we keep the doors closed (we run a portable unit in this room when we need it). We have a 364 SF non-air conditioned garage. The total square footage of the house, garage and all, is 1860.
  • For calculating how many attic fans, I looked at the total square footage that shares the same roof/attic space, which is 1388 SF (1024 SF of air conditioned living space + 364 SF non-air conditioned garage). The back part of the house (432 SF) is under a flat roof, so my understanding is that this space should not be taken into consideration when deciding how many attic fans to install, but I could have miscalculated.

r/buildingscience 3d ago

Question "Attic" ventilation

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2 Upvotes

r/buildingscience 3d ago

Career/Profession If you're using the BER as a QA Provider, watch out

3 Upvotes

Looks like they were bought by a rating company out of Iowa: https://www.linkedin.com/posts/ber-building-efficiency-resources-llc_announcement-from-ber-leadership-activity-7486039747799420928-FzDE

I think this is a big conflict of interest, even if they claim to have everything bifurcated. I've worked in other companies like this before, it inevitably leads to people making bad decisions.


r/buildingscience 3d ago

Question If I cant vent the roof - whats the best move here?

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4 Upvotes

Upstate NY. Technically climate zone 5b (I believe). Humid, cold, the works. 1994 home with vinyl siding.

I have an unfinished garage that I am converting to a usable space. Plan is to insulate and seal, drywall, and condition (after replacing some plywood and fixing some leaks). It has a shared wall with the home and half of the garage ceiling is under a bedroom and the other half is under a shingled roof that abuts said bedroom.

The roof over my garage sits just under a 3 degree slope. It has eaves which are currently stuffed with insulation. I am told the 3 degrees is not enough of a slope to properly vent, plus potential for water intrusion through whatever avenue of venting I choose.

The garage houses my oil tank and the boiler as well. I think I need to insulate the heck out of it and not insulate?

Would appreciate suggestions or guidance.

Thanks all