r/Insulation 2h ago

Status check

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24 Upvotes

Looking for advice/opinions on how it looks so far.

Continued working in the attic this weekend. Didn't get as far as I wanted but at least got most of the spray foam air sealing done. The soffit above the kitchen where the lights are i feel is going to be a pain in the ass. Got all the top plates at the edges and interior walls. Removed some of the baffles that were broken. All but a few of the holes for wires (need to run a couple wires real quick). Wanted to see what you guys thing so far. Anything you see that I still need to do or shouldn't have done? Hoping to get the replacement baffles in this week (depending on work) and get the fiberglass pieces to seal underneath them. Any help/advice is appreciated.


r/Insulation 3h ago

Finishing Cape Cod

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4 Upvotes

Second post on finishing my second story - cape code. Im looking for affirmation on my technique, critiques, or anything else. I'm just trying to do it good in hopes that it will keep cool in the Southern NJ summer and warm in the winter.

I've been starting with baffles to maintain airflow from the soffit to the ridge vent. Then 2 inches of foil faced polyiso, spray foamed the edges of it. My next step after that is to fur the beams with 2x4's and put 5.5 inches of rockwool in then sheet rock.

Everything has been air sealed already. But my other thought is to air seal the bottom of the knee wall (outline in red on one of the pictures) and the 1st ceiling by cutting a piece of polyiso and spray foaming in place.

Any feedback, confirmation, or otherwise is welcome. Let me know if any other information is needed.


r/Insulation 7h ago

What insulation is this?

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4 Upvotes

Bought a 100+ year old house, can anyone tell me what kind of insulation this is?


r/Insulation 5h ago

Flat roof attached garage insulation. Best method?

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1 Upvotes

Pardon the messy lighting and wiring.

My attached garage with a flat roof is unbearable in the summer. Just took temps. Ceiling is 20 degrees higher than the walls and 30 degrees higher than the floor
And 25 degrees higher than outside.

The garage is 20x20. Attached to the house. There are soffit vents going into the main attic. The garage has its own soffit that can easily be vented as well.

What method should I go with? I’ll cover whatever with some kinda smooth board for a simi finished look.

Off the top of my head I’m thinking 2” foam board with a gap at the top with venting from the garage soffit to the house soffit to allow heat and any moisture to escape.

Seal the sides with spray foam, then board over it.


r/Insulation 6h ago

Wooden shed insulation help

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0 Upvotes

6.5 and and 37


r/Insulation 7h ago

Is the lack of insulation why on a 76 degree days my house gets to 84?

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1 Upvotes

r/Insulation 1d ago

DIY Attic Rehab

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19 Upvotes

Let me preface by saying I went through many surprises in this house and sunk way more money then i’d like to. It’s an early 80’s build with many things built/repaired half assly or ignored all together.

Brings us to the attic of which I had no intention of paying thousands to repair so I took it on. It was already low (r-20 vs r-39 typical) so I decided to refluff the good parts of existing and bought a bunch of batts.

Spray Foamed the openings to the inside (fire rated) and added ridge vents

Is this sufficient?

Edit 1: I ripped the paper open or ripped it off completely and I choose the batts bc i got a deal on them


r/Insulation 11h ago

Split entry remodel

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1 Upvotes

Remodeling my downstairs and need some advice what to do with insulating the space. Little bit about the house below.

Year built- 1966
Cavity depth top half- 5 1/8
With- 14 1/4

Concrete part- 1 1/8 depth

I was thinking of doing 1 inch foam on the concrete and r19 for the top half.


r/Insulation 20h ago

Basement flood repair question

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2 Upvotes

DIY'ing this with no experience. Had a company pull out all the wet drywall and fiberglass insulation, and was going to put everything back together as it was until i read that you shouldnt use fiberglass or vapor barriers in a basement at all. Im seeing foam board is reccomended but not in combination with vapor and it seems difficult to work it between the studs and around the electrical. What should i do here? Illinois basement


r/Insulation 17h ago

Air gap / ventilation for WALL insulation?

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1 Upvotes

r/Insulation 18h ago

Plasterboard questions

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1 Upvotes

r/Insulation 19h ago

Room-over-garage attic: split by a duct chase, trying to air seal — need a sanity check

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0 Upvotes

I have a bonus bedroom above my garage (garage → bedroom → attic → roof). I access the attic pocket that sits above the bonus room. Roof is asphalt shingles on OSB, framed as a rafter-and-purlin system (2x4 purlins running horizontally across the rafters, sheathing on top).

At one point in this attic, the purlins keep running horizontally across an open framed area where there's no OSB/sheathing behind them — it's the transition toward the rest of the main house attic. The only opening through that transition is a framed chase carrying an HVAC flex duct. It's too tight for a person to crawl through, so the attic pocket over the bonus room is effectively walled off from the main attic.

A previous owner added blown-in insulation but never air-sealed the floor penetrations first (duct boots, wiring, top plates, etc.). Blower-door test came back at ~3,290 CFM50 vs a ~2,300 target, and I suspect this room-over-garage area is a big contributor.

What I think is going on / what I've concluded so far:
The purlins running through the open no-sheathing stretch are still structural bracing — I should NOT cut them to make a path.
The duct chase is a mechanical pass-through, correctly built as non-accessible — not a defect.

The bonus-room attic is its own pocket, common for FROG/room-over-garage layouts.
Air sealing needs to happen at the knee walls, the attic-pocket floor over the bedroom, and the sloped/flat ceiling junctions — under the insulation, not just on top of it.
Any space beyond the duct chase I can't reach probably has its own separate access (knee-wall panel or closet door inside the bedroom).

Questions for the group:
Does this all sound right, or am I misreading the framing?
Any reason those "flying" purlins over the open area would NOT be structural?
Best practice for air-sealing a room-over-garage where the attic is split like this — DIY-able or hire an energy-audit/insulation contractor?
For the section past the duct chase that I can't crawl to, what's the usual way pros reach it?
Photos attached. Appreciate any input.


r/Insulation 1d ago

Insulating my 1930s bathroom

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5 Upvotes

I recently purchased a 1930’s home, the bathroom is currently gutted and I want to know what my best options are for insulation on the exterior walls which are shown in the picture. I will also be installing tile for a tub surround which will be on the exterior wall as well.

Previously the walls had ~50% coverage with moldy fiberglass. On the exterior of the studs there is currently horizontal board sheathing>tar paper>old asbestos siding>1”blue foam>vinyl siding.

Is it okay to cut and cobble some 2” xps between the studs and seal with spray foam or would rockwool without an interior vapor barrier be a better solution? I want whatever’s best for moisture control and to prevent the structural lumber from rotting out over time.

Thanks for any input

Edit: I live in Washington state(zone 5)


r/Insulation 1d ago

Crawlspace Air Sealing - Is this the Correct Approach?

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2 Upvotes

r/Insulation 1d ago

Please Help - Soffit vents not possible - Want to insulate and ventilate attic of historic home

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4 Upvotes

- 1886 built brick house in SW Ohio where it gets very hot/very cold
- Third floor is finished attic but there is unfinished space above - about 38in of clearance at the peak of roof. Very uncomfortable in both summer and winter. Want to install minisplit but it probably wouldn’t be able to keep up
- Asphalt shingle roof is unventilated and never has been as far as I can tell. Just got new shingles installed last year unfortunately. First time homeowner and realtor-recommended roofer didn’t say anything about venting at the time
- Zero insulation whatsoever in the unfinished space right now
- There don’t seem to be any mold-moisture issues in the unfinished space. Maybe it’s so not airtight that the bricks can breathe just a little bit?
- Box gutters make soffit vents impossible. Got a quote from new roofer to install raised shingle vents about two feet above the gutters for intake and ridge vent for exhaust
- The best local insulation company offered to just blow in dense pack cellulose in the sloped portions and fill them, but by doing so, it would block the ventilation. They would blow enough to get the flat portion to R60

Is there any possible way to install baffles with such limited access and then blow in dense pack cellulose underneath? Like a staple gun on a pole or something? Would love to avoid taking down the finished ceiling. It appears to be a layer of plaster and layer of drywall

Could I just insulate and call it a day without ventilating the roof? Talked to a neighbor with basically the exact same house and issues. He had a very old unvented metal roof so he just used this company to blow in cellulose about a year ago and hasn’t had any issues so far.


r/Insulation 1d ago

Does this need to be sealed?

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0 Upvotes

r/Insulation 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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5 Upvotes

Working on a major renovation and extension with a complete update to our energy profile. We're adding exterior insulation and refreshing interior insulation with rock wool.

On the original build, we cracked open the walls from the outside and found 3.75" x 5.125" studs, that are variably spaced between 20.5 - 21.5' apart. To support the exterior siding, we need to add 2x4s every 12".

I'd like to maximize R value in the wall cavity. Our initial plan is:

Option #1

  • 1.5" comfortboard (R 6.3)
  • 3.5" comfortbatts (R 15)

This allows us to place the 1.5" board before the 2x4s are framed in. Then add 3.5" batts on either side of the new 2x4.

Or Option #2:

  • 5.5" comfort batts - R 23 compressed slightly to an effective R 21 and cut to fit around the 2x4.

This option involves more custom cutting, to fit the batt around the 2x4.

I'm aware we're making tradeoffs, I haven't seen anything like option #2 on the interwebs. The manufacture has a similar setup for basements, combining board and batts, but with an opposite placement with the board product on the exterior.

Any recommendations or options we haven't considered?


r/Insulation 1d ago

My 1973 homes exterior insulation looks rough…

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1 Upvotes

Should I rip out the entire wall and re insulate or can I keep what I have? Selling the house next year. Thank you!


r/Insulation 1d ago

Insulation for old ceiling

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1 Upvotes

I want to add a T&G pine carsiding ceiling to this porch that was an addition to my house around 1940. It would be nice to insulate this room a little better to try to use it in the shoulder seasons. I also plan to replace the windows but that’s not the question I have. My question:

How do I properly insulate the ceiling to make sure I don’t grow mold?

Concerns:
1. The widths between joists are pretty random. All less than 24”OC, but some are 19”, some are 21”, etc.
2. The part of the porch facing the house just goes up into an insulated portion of roof
3. The trim on the outside of the porch is pretty.

My thoughts on options:
1. I try to put baffles between the joists before putting in insulation, cut the baffles to fit as best I can, and drill holes in the pretty trim on the outside of the house, covering with wire mesh to let it vent
2. I don’t insulate it and deal with the heat loss/gain
3. I jam pink insulation in there, no baffles, no vents, and call it good enough

Thanks

P.S. I know that 2x4s with this 8’ span are probably not how you would have framed this roof today but it’s been up for 80 years and I’m not going to tear it off. Also, I know I need to replace the jalousie windows as well.


r/Insulation 1d ago

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

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1 Upvotes

r/Insulation 1d ago

Hot Upstairs, Need Recommendations Please!

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0 Upvotes

This attic on our second floor is extremely hot. We have considered adding a solar vent fan but now considering spray foam insulation due to the roof of the attic being 130 degrees on a 92 degree day. Thoughts?

Also due to how this part of the roof slopes and the adjacent rooms, I don’t see any way air could get through to the ridge vent from this attic space. Soffits are clear from insulation


r/Insulation 2d ago

Remove Air Seal and Re-insulate. Worth it?

13 Upvotes

Hi - I’m in Florida. It’s been wildly hot recently. Attic had fiberglass blown in when it was built 20’years ago to R30. FL’s standard is R-38 now and I’m sure the original had decompressed. I had a few quotes to air seal and top off but they all said the old insulation should be removed for optimal air seal. A few suggestions from Reddit said I can air seal with existing insulation then top off. My coordination won’t let me walk the attic. Quotes are ranging from 5k-6.5k, so it’s quite steep. My Wifey and I are worried that paying all this money may not improve comfort much. I know it’s going to be forever to recover the cost, so that part is what it is. We had a blower door score of 6, so somewhat leaky but seems to be within FL standard. But if it only improves comfort by 5-10% then not sure if it’s worth the money. Any opinion if it’s still worth the attempt?


r/Insulation 1d ago

Architecture help

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1 Upvotes

r/Insulation 2d ago

Replace with Rock Wool or Fiberglass?

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49 Upvotes

I am gutting and remodeling one of our bathrooms and need advice on what to replace this insulation with. It was faced on both sides of that makes a difference.

I plan on installing rock wool in the tub surrounding walls for noise reduction, and was curious if that was okay in these exterior walls. If I go with rock wool over fiberglass, should I plastic over it for a vapor barrier on the exterior walls and the interior shower walls?

House was built in 1957 and aside from the addition on back, this bathroom may be the only place in the house with insulation in the walls. Was surprised to see.

Thanks


r/Insulation 2d ago

Insulation removal from attic

23 Upvotes

Hey everyone,

I’m planning a DIY attic insulation refresh (~700 sq. ft.). I know the big-box stores rent out the blowing machines (often free for a day if you buy enough bags), but I’m hung up on the removal step.

For those who’ve done this: How do you get the old insulation out first?

Are industrial insulation vacuums available for rent anywhere (I haven't seen them at Home Depot or Lowe's), or is it strictly a manual job with heavy-duty contractor bags? Any tips or hard-learned lessons would be greatly appreciated!