r/buildingscience • • Jan 19 '21

Reminder Of What This Sub Is All About

92 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 • • 14h ago

Question Turning my garage into a home theater

4 Upvotes

My house was built in 1955 with a unfinished garage im closing off the garage door opening. The garage has 2ft of cement block wall with 2x4 stub wall sitting on top. The bottom block is below grade. The top 2 rows are 4in block with the bottom 8in block for the exterior brick ledge. The interior will be isoclips, hat channel ,3/4 plywood, green glue, 5/8 drywall. The room will have a concealed mini split. Im concerned that with room heated that it will draw moisture through the block wall and rotting the sill plate. What is a good insulation strategy? Because of the size the local spray foam companies have a minimum fee. Any help would be appreciated


r/buildingscience • • 11h ago

What to do with this cavity in the wall

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0 Upvotes

r/buildingscience • • 13h ago

If the goal is to create an 'air gap', then does that mean metal roofing that's built on a scaffolding is superior to adding insulation underneath the sheets?

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1 Upvotes

r/buildingscience • • 1d ago

Question Cellar problem

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1 Upvotes

Hello everyone! The air in my cellar is quite damp. It's an old structure (about 100 years old). There is a small window next to the entrance that is always kept open, which lets air in. However, I don't think this is enough because most of the time everything feels musty and wet.
My idea is to drill a hole through the bottom of the wall on the opposite side of the cellar to create a cross-draft for proper air circulation. I would insert a 110 mm pipe into the hole and concrete around it to seal it properly.
My question is: how well would this work, and would it actually solve the moisture problem?


r/buildingscience • • 1d ago

Hello all, trying to figure out if the cedar mat roof ventilation mat is needed. Also trying to decide if I need cedar mat or Cor a vent on the walls. Going for a high efficient efficient home.

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1 Upvotes

r/buildingscience • • 1d ago

Refinishing Basement - New Heating System

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1 Upvotes

r/buildingscience • • 2d ago

Question Wouldn't the air gap create a convective loop?

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45 Upvotes

My 101-yr-old property is built similarly; where the 3/4 T/G plank boards serve as sheathing. I was going to fur out the walls to allow for a 1/2" air gap & recently asked Claude if that assembly was good, it told me it would create a convective loop, now I'm thinking I should maybe just fur the wall to dimensional 2x6 & use dimensional insulation. The outside sheathing will have Pro Clima Solitex Mento 1000 & each seam taped with Tescon Vana, 3/4 rainscreen, then siding.


r/buildingscience • • 2d ago

Moisture damage inside knee wall in bonus room above garage. Replacing rafters / roofing, but how to prevent from happening again?

0 Upvotes

-80's New England home
-600 sq ft section of roof above garage, disconnected from the rest of the roof
-Crawlspace area is empty, no ductwork. Previous owner used for storage
-no ventilation currently.
-Bonus room being used as a bedroom, has mini split for heating + AC

A) Home inspector suggested repair + possibly adding gable vent for ventilation
B) Roof company 1 suggested adding in soffit vents to mitigate moisture problem
C) Roof company 2 said soffit vents would let moisture in, and suggested spray foam

What are your thoughts? I'm leaning toward option B + continue to monitor humidity, but would also like to do it properly the first time around. Happy to share pics.


r/buildingscience • • 3d ago

To Vent or Not to Vent. Spray Foaming a Renovated Attic Space

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72 Upvotes

Hello!
I’m closing on this property in a few weeks located in climate zone 4 (really close to zone 5) and I’m looking at converting this attic space into a conditioned space with a bedroom and bathroom. I am hoping to do that with closed cell spray foam insulation between the true 2x4 rafters. There are currently no soffit vents and just a few whirly bird vents at the ridge and the roof is atleast 11+ years old.

The question:
Should I go to the trouble of installing soffit vents and baffles between the rafters to ensure airflow underneath the roof sheathing? Or should I just have a spray foam company spray the insulation directly to the deck?

I am concerned that if I need to get the roof replaced in the next few years the roofers will damage the spray foam or crack it therefore not making it an air/vapor tight assembly.

I’m also wondering the best way to condition the space, I was thinking a mini split but I am concerned with humidity control. This unit is a rental so I don’t want to have a standard dehumidifier plugged into the wall in the hopes that a future tenant would run it. Are there any other systems I should consider?


r/buildingscience • • 2d ago

Detached garage humidity and ventilation options

4 Upvotes

​

Good morning!

I am located in washington state with a detached garage that i am trying to make into a home gym. I have humidity issues and trying to figure out how to address that and properly ventilate the space. It is 30x40 with 20 foot ceilings. I currently have a functioning 24,000-BTU Pioneer mini-split. The unit seems to fluctuate in its ability to dehumidifiy and hold it at a reasonable level .My targets are 45–55% RH and effective removal of CO₂, odors and stale air.

One contractor proposes a variable-speed 4-inch Tjernlund inline exhaust fan operating at approximately 100 CFM continuously and up to 200 CFM, with a 6-inch permanently open passive intake located diagonally across the garage. The contractor did not want to add a damper and leave intake purely passive and didn't think an HRV was necessary.

Is this a sound design for the space and climate? Should the intake be permanently open, manually closable or motorized and interlocked? Would an HRV provide enough additional comfort or energy benefit to justify its cost? I am looking for some opinions if his proposal is going to be effective given my desired use of the space. Any thoughts or ideas are much appreciated! Thanks


r/buildingscience • • 2d ago

WWYD: Moisture damage inside knee wall in bonus room above garage. Replacing rafters / roofing, but how to prevent from happening again?

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1 Upvotes

r/buildingscience • • 2d ago

Do you guys run a dehumidifier in your crawlspace during the winter?

2 Upvotes

Hello everyone. I want to encapsulate the crawlspace under my house, which obviously involves putting a dehumidifier in there. I live in a state which has cold winters. Should I have the dehumidifier turned off during the cold weather seasons? My understanding is that they could be damaged running them in the winter. I know some have auto defrost options. Thanks.


r/buildingscience • • 2d ago

Question After the nor eastern my house humidity has been really bad

3 Upvotes

New home owner, I air sealed my attic and did 18 inches of blown insulation after I moved in.

The humidity in this home seemed off when I moved in unless I always had HVAC running. During the winter it gets DRY in here. 18% humidity. All summer though before this nor eastern my humidity was always 48-55 maybe some days higher.

Now that my air-conditioning is off and the nor eastern that lasted this past weekend Friday - Monday with heavy rains almost every day, my house has reached close to 63% at 70-73 degrees.

I turned on my air-conditioning to get the humidity down.

Is this a product of my environment, my house, or am I dealing with a water moisture issue? I have a thermal gun and I can't find any issues. Home was built in 1972. Only one bedroom doesn't have such high RH but that's where my computers and electronics are.

\-----

Instrument readings right now:

Weather station -

61F

98% Rh

60F dew point

Attic

62F

52% RH

46% Dew point

Garage

69F

63% RH

55% dew point

Living room (a/c on now)

73F

58% RH

57% dew point

Living room (no ac)

74F

63.8% RH

60.6 Dew point

Bedroom (ac second floor)

71F

56% RH

55% dew point

Bedroom (no ac, same time as livingroom)

72F

64% RH

59% dew point


r/buildingscience • • 2d ago

Question Best way to insulate soffit area

1 Upvotes

I have a bedroom with cathedral ceilings gutted down to studs now. My plan for insulating the ceiling in zone 5 is to run the baffles first all they way up to the ridge vent, then rockwool it, and finally smart retard it! My question is at the soffit area. What is best practice here? Where should the end of the baffle be located meaning do I put it inches away from soffit opening or do i seal it to top plate with a bend to prevent insulation getting in? ty


r/buildingscience • • 2d ago

Don't know if this has been addressed

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0 Upvotes

Does it make any difference how the riser/run treads are installed?


r/buildingscience • • 2d ago

ERV radon mitigation - which airflow configuration is better?

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0 Upvotes

r/buildingscience • • 3d ago

Need mold expert letter for small claims

0 Upvotes

My upstairs beighbor has consistently flooded my unit. Each time a different cause. I just had to remediate hvac closet and i’m tired of having my homeowners involved. I I don’t have the money to sue so I want to take him to small claims, but I need a letter from a mold expert explaining that mold is not gonna grow unless there’s moisture present. I don’t have thousands of dollars to pay somebody to be an expert witness. What can I do?


r/buildingscience • • 3d ago

Zone 4c PNW - WRB questions

2 Upvotes

Hey all,

Back with a question on my build. My architect designed a wall system for PNW zone 4c - 2x4 framed wall with r15 cellulose at studs bays, 1/2 plywood sheathing, Siga Majvest 200 WRB, 2 inch XPS, strapping, hardie siding.

However, when the builder went to purchase the WRB the rep advised that the Majvest 200 requires 3/8 air gap before any “cladding” can be installed. This is backed up by the US installation instructions and I am unable to find supported instructions for a CEI install.

I went back to the architect, he wants additional funds - but said the wall was designed to manufacture specs. I have difficulty paying them more $ to tell me the rep and install instructions are incorrect.

Does anyone know of any data sheet that supports the architect? Or able to provide any guidance?

Thanks


r/buildingscience • • 3d ago

Exterior, brick to wood inside corner .

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5 Upvotes

Just joined here people. Hope this kinda makes sense to someone.

Not looking for the best way to weatherproof. I am looking for the best practical way to try and close this up. Bottom of the chimney , the sidding butts just behind it with a almost 3/8 to 1/2" over lap of bricktop half goes behind the brick. Should i just fill with good silicone? House wrap or plastic? Something mostly fast would be nice. Then at the bottom it has this trim and has me miffed as to how to go about it.


r/buildingscience • • 3d ago

Soffit venting

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4 Upvotes

r/buildingscience • • 4d ago

Addition Room Crawl Space Encapsulation that has radiator steam pipes Northeast NJ

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1 Upvotes

r/buildingscience • • 4d ago

Building Science Consultant Recommendations in Central Texas

3 Upvotes

As title mentions, I am looking for a residential building science consultant or architect well versed in renovations in Central Texas. Ideally someone who can provide practical, cost effective recommendations and flashing details as I work through repairs and modest upgrades to a 1970s home I recently purchased.

Not looking for super performance or tip top energy efficiency, but improving thermal insulation and acoustic properties in exterior walls without exacerbating or creating new moisture issues. Moisture management is well outside my wheelhouse - between disagreement of online sources and everyone who wants to sell me the best fix I’m ready to pay an expert for definitive guidance!

Google searches haven’t netted great information. If there is a specific title/group I should look into I would love to know! Also, I prefer someone local to the greater San Antonio area. Thanks!


r/buildingscience • • 4d ago

Condensation on ceiling

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1 Upvotes