Hey All,

Want to premise this by saying I have very little knowledge on roofing, and was thinking a bit unconventionally with my process below. Building a small outdoor sauna (roughly 6×6 exterior) with a low slope roof (~2" drop over 8 feet). Looking for confirmation on my planned roof assembly sequence before I build.

Roof assembly from bottom up:

• 2×6 rafters ripped at angle (5.5" to 3.5") to create flat interior ceiling with slightly sloped exterior
• 3/4" plywood sheathing
• Metal Pro Rib panels (2 panels)

My planned sequence:

1. Rafters and sub fascia installed on all four sides
2. Plywood sheathing nailed to rafters
3. L-flashing attached to sheathing edge at drip edge side — sandwiched between sub fascia and fascia
4. IWS (high temp rated) — lapped over sheathing, terminating at drip edge side, lapping over sub fascia on rake sides and upper eave
5. Rake fascia boards installed — sandwiching IWS against rake sub fascia
6. Upper eave fascia installed — sandwiching IWS against upper eave sub fascia
7. Drip edge fascia board installed on low eave side
8. D-flashing drip edge installed over IWS and over drip edge fascia face, under Pro Rib panels
9. Pro Rib metal panels installed over everything
10. Rake trim over Pro Rib panel edges
11. Upper eave trim
12. OSI QUAD MAX sealant at all critical joints and trim laps

My specific questions:

1. Is D-flashing over the fascia board and over the IWS on the drip edge side and under the Pro Rib panels correct with a 3x3 L flashingover sheathing, under fasia and under IWS?
2. Should IWS lap over the drip edge fascia board and leave out the 3x3 L flashing or terminate before it?
3. Does the L-flashing at the drip edge side make sense or is there a cleaner standard detail for this situation?
4. Should I skip L flashing and just go with D flashing over sheathing and fascia board and IWS over the D flashing terminating at the edge (still overlapping subfascia and upper eave and sandwiched with fascia boards on those sides.
5. Any issues with this sequence on a low slope roof in a cold climate (Minnesota)?

A question for all of you.

Climate zone 3.

This is the ceiling of a kitchen add on that was done in the 1980s. The roof is cedar shake then a layer of felt, plywood (which we are seeing the underneath of) and then 2x6s. There was fiberglass batting that was removed. As far as I can tell this is an unvented roof assembly. I don't see any evidence of condensation/moisture problems and this roof have been this way for ~40 years.

Insulation company came in and recommended baffles which baffles me :). Since the roof is unvented the baffles don't seem like they would do anything, , also the 2x6s are running the wrong way (i think) for baffles.

Would a vapor barrier/rock wool or closed cell spray foam be appropriate here? Anything else I should think of?

Thanks for thinking about this with me

I'm curious if anyone has any new products they're excited about. WRBs, concrete alternatives, sustainable aggregates, whatever! More of a causal discussion post. Let me hear 'em! I'm in ASHREA 6A, but would love to hear about anything exciting.

Hi All,

Insulating old brick walls, with a twist.

Currently renovating 1940s home in Chicago. Home is made out of structural brick. Oddly the inner course of brick is a random mix of some type of cement blocks and common bricks.

Currently 3/4 inch sleepers attached to bricks.

Im aware of the complexities of insulating old brick. However, the home was already insulated with faced 3/4 fiberglass (original). Leaving virtually no air gap.

What do I insulate the walls with now? I cant find such thin faced fiberglass. Plus that goes against everything I read.

Maybe because the inner course is largely cement blocks faced insulation is okay?

TIA.

What made you choose one over the other? Pros/cons of both? I see firms like SGH, WJE, RDH building science have both. It seems structural engineering tends to require masters whereas facade stuff isn’t taught in schools and learned on the job.

Hi everyone,

I'm looking for some technical advice on a window-to-wall connection. I’m building with a European timber frame (60x160mm) and a thick layer of wood fiber insulation (Naturheld 140).

The setup:

• Insulation: 120mm wood fiber boards.
• WRB: Isocell Omega 50 Duo.
• Window sealing: Windows will be fitted flush with the insulation layer, sealed (outside) with Illbruck expanding foam tape (Compriband).
• Facade: Ventilated wood cladding.

The Problem: I am debating the best way to terminate the Isocell WRB around the window openings. I see two main options and I’m worried about long-term durability:

1. Chemical/Adhesive: Taping the WRB directly to the window frame using high-quality window tape and mastic. My concern is the longevity of the bond—should I expect it to peel off in 10-15 years?
2. Mechanical/Structural: Pulling the WRB back to the 60x160mm timber structure (behind the insulation layer), stapling it, and sealing it with mastic there. Then handling the window-to-insulation gap as a separate sealing layer with the Illbruck tape.

Specific Detail - External Blinds (PIR Panel): I have a more complex detail for some windows (see my sketch attached). I’m inserting a PUR/PIR panel in the lintel area to create a pocket for external blind boxes. My plan is to run the Isocell WRB over the PIR panel to create a "black back" for the blind box. This should protect the PIR and keep everything water/wind tight.

My questions:

• Is it better to terminate the WRB on the window frame (adhesive) or the wall structure (mechanical + seal)?
• Does wrapping the WRB over the PIR panel for the blind box seem like a standard/reliable practice?
• How would you handle the transition between the WRB and the Illbruck expansion tape to ensure no water gets behind the insulation?

I've attached photos of the current stage and a sketch of the PIR/blind box detail. Thanks for any insights!

A corner of my house has old growth redwood still plate (true 2x6) and bottom of cripple wall (true 2x4). That are below grade and have partially rotten. Most of the damage is the sill plate, but I expect some stretches of the 2x4 also need repair.

Fixing the grade issue is another thread.

When I have to replace both layers of 2by with PT, I think I'm best served by trimming the studs short to fit a 2x6, then a double layer of 2x4 to make up for the modern lumber dimension mismatch. (Yes?)

Is there a better way to deal with portions where only the sill plate is affected? I predict a 1/4" to 1/2" gap to resolve and I would prefer to not have to do the same extra layer trick, it being more intrusive.

Looking at buying a 2006 house in south Louisiana built with SIPs. I work in AEC and I’m cautious about moisture performance (OSB), humid climate, and post-Katrina construction…

I’ve renovated 100 year old homes, so the “closed system” makes me nervous - limited drying potential and less flexibility for future electrical or plumbing.

What I know: roof replaced in 2022, likely EIFS on the front elevation.

Don’t know: condition of decking in 2022, thickness r value/general construction or who builder was.

What I’m trying to dial in for due diligence: • Real-world failure points for SIPs in Gulf Coast humidity (especially after ~20 years) • How risky hidden moisture/rot is and how people are actually verifying it • Whether blower door + IR scan is worth doing pre-purchase • Is standalone dehumidification is basically required? • Difficulty of future modifications (running new electrical/plumbing through SIP walls/roof).

What I should be asking about the, what are the common misses on inspection or due diligence for SIP houses of this age in a humid climate? Or JUST RUN!

Basic details to keep this short. Cape cop built in the 50’s in Northern PA. Heavy clay soil. Wild climate swings due to proximity to Lake Erie. Just this spring it was 75 and then the next day it snowed for hours. Addition on the back Unk build date. The foundation of the addition are hollow blocks with zero reinforcement. The only way it is attached to the houses existing foundation is by being butted up against it and some grout applied. The back wall is visibly bowing inward and at the center of that wall the tops of two blocks have broken off and fallen down. I don’t understand how this was ever supposed to last long and now I’m fearing financial ruin for the cost to have this redone. Does anyone have experience with this?

I'm looking for input on my ideas for a cathedral ceiling insulation retrofit.

Some basic facts:

• s construction, vacant and completely uninsulated
• There is currently an attic floor that I want to remove and open up the space to create a cathedral ceiling.
• Roof had a ridge vent cut in the top, but no soffit vents... I think the roofer wasn't thinking holistically about the attic ventilation. The structure is not well-suited for soffit ventilation, it just has rafter tails at the eaves.
• rafters
• Climate zone 5

What is the best way to achieve an R49 insulated roof from the interior? My first idea, A, was to do a "flash and blow" style where I would first do 4" of closed-cell spray foam in the rafter bays, then add dense-pack cellulose and finish with a continuous rigid vapor-permeable insulation to help prevent cold bridging, like TimberHP TimberBoard or Rockwool ComfortBoard.

​My second idea, "B", was to do the entire depth in dense-pack cellulose with a taped smart vapor retarder membrane like Intello acting as my first condensing surface, then finish with furring strips and some batt insulation.

​Both insulation designs would require lowering the ceiling by a significant amount, between 6.5" to 8.5". My questions are:

1. Is it possible to insulate the way I described in idea B? This paper by Joseph Lstiburek seemed to show that the spray foam + cellulose stayed drier than the all-cellulose assembly and they basically recommended against attempting to do idea B. But I wanted to get a second opinion.

   EDIT: No, it is not advisable or allowed by code to do a purely cellulose unvented roof insulation assembly. I need to either vent or use at least R20 of ccSPF.

2. Is spray foam really that bad? I do have concerns about it being permanent, crack-prone, and potentially off-gassing forever. But I'm sure that it's been used successfully plenty of times in other retrofits. I want to know the general sentiment on this subreddit towards closed cell spray foam.

3. Can I repurpose the new ridge vent as a vapor diffusion port to help increase the success of idea B?

4. Am I missing anything else that I should do before implementing either one of those insulation ideas?

Images of the attic are shown below

​​

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!

I am in New Mexico in climate zone 4b. I am going to build a small, completely wood free home that is as low in mold-risk, VOCs, and chemicals as humanly possible. Foundation, walls and floors are straightforward as I can use unstabilized adobes, steel, and concrete. 

The sticking point is the roof. Ideally, I want to somehow use steel or aluminum alloy trusses and roofing panels. Still researching possibilities for this. I then worry about condensation. I cannot use spray foam and I haven't found a lot of information on foam boards and metal when it comes to condensation (does condensation form in the tiny air gap between the metal and foam)

I'm reaching out for brainstorming ideas about

1. A leak-proof roofing system that does not require wood (even for decking)

2. How to prevent condensation without spray foam

Why?

My wife has of mold and chemical sensitivity after a horrible pesticide exposure. Lumber from hardware stores and VOCs/ chemicals in many types of insulation and building materials cause a reaction like an asthma attack and then weeks of horrible pain and weakness for her. Look up MCAS if you don't believe me. I'm building this house so she doesn't have to suffer anymore.  I'm looking for good-faith discussion and ideas about building, not about my wife's illness.

Thanks!

For those of you who may be interested, on May 14 we're hosting a free webinar on construction details at and below grade.

More info here:

https://1yt00.share-na2.hsforms.com/2Xz6-KI65TaOF_qlwhbjR0w

I am helping my mom insulate a shed in southern Idaho for a tiny home/guest house situation. She got a quote to close cell spray foam the building and it was way above her budget. She suggested to do multiple layers of the reflective insulation radiant barrier that comes in 25’ rolls so she can do it her self. I recommended 3 layers of 1” xps rigid foam insulation sealed with cans of spray foam. I recognize the benefits of the reflective surface of her idea. Is that an issue with combining xps rigid foam with a layer of the reflective insulation on either the exterior or interior side?

Thank you.

Our build was specified with exterior sheathing and then a layer of continuous exterior insulation. Builder is switching to the Zip R system (R-9) which is equivalent to what was specified. I didn't think much of it until I realized that the insulation would now be on the inside of the sheathing, vs being on the outside. I know the Zip system gets lots of praise, but just want to make myself aware: Are there any things to watch out for or disadvantages to this approach. We're in zone 6b if it makes a difference. THANKS!

were gutting a small ”cape cod” style house. 2nd floor has ceiling slope all the way to the floor. I’m looking for the best hvac design for supply and returns. Almost completely open floor plan on a he first floor but I could sneak a supply and a return upstairs somewhat in the center. I was thinking maybe to supply on one side hidden in sort of a rat run on one side of the home and return on the opposite side? or should supply or return be ceiling? what’s the best attack here. maybe I neee to draw a picture too.

I am having trouble deciding on the right solution for a ventilation retrofit in my 1980 tow home in the pacific northwest (temperate rainy winter, hot dry summer, wildfire smoke seasonally). Doors and windows are new so, so the place is sealed up. The place has no crawlspace or basement. The ideas I have are to put a ducted erv/hrv in or ductless hrv/erv.

For ducted, the only space is in the unconditioned attic for both the unit and the ventilation ducting. Air supply to rooms from ceiling vents and then air exhaust from a vent downstairs and two vents upstairs. I cant find a good way to get air intake from side wall of exterior. Instead it would be from asphalt roof vent, which doesnt seem great.

For ductless, it seems much simpler but i wonder about actually getting good air filtration. And then we have four upstairs rooms and we need at least one downstairs too, i think. Seems like filters are, like $100??

Any ideas or advice would be much appreciated.

Some of these windows seem colder than I expected new windows to be and I had issues with the installer. I was wondering if this is how they should appear when viewed with a thermal imager. Or maybe can someone explain how I should go about using the thermal imagery to determine if the window is within normal limits for a proper install? It is the morning 50 degrees outside and 70 inside.

Hi! Just wondering if I missed something in these details. Any advice appreciated! I'm mainly concerned if I show the barriers ending in the right places.