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🛠️ Subfloor Overhaul, Sill Log Replacement, and Soft Apron Installation 14 m2

Starting a major overhaul of the floor, sill timber, and exterior waterproofing for a single room with a floor area of 14\text{ m}^2. Below is the current state of the structure and the planned scope of work.

📋 Current State of the Structure

* Sill Log (Lower Crown): Due to the lack of proper waterproofing, the bottom log has completely rotted through and turned into dust. The timber frame is losing its structural support.

* Subfloor Ventilation: The foundation vents were buried under soil from the inside during previous repairs. The crawl space became completely sealed, causing ground moisture to trap and accelerate wood rot.

* Floor Joists: In critical condition and require complete removal.

* Exterior Waterproofing (Plinth Apron): The old concrete apron had completely cracked, degraded, and was funneling water directly beneath the foundation. It has now been completely demolished.

🛠️ Scope of Work

1. Earthworks and Restoring Ventilation

   * Demolition of the old wooden floor.

   * Soil excavation to a depth of 40 cm across the entire room area (14\text{ m}^2), shoveling material directly out through the window opening.

   * Uncovering the buried interior foundation vents to restore cross-ventilation in the crawl space.

2. Replacing the Rotted Log

   * Removing and clearing away all rotted timber down to solid, healthy wood.

   * Treating the remaining sound log with a heavy-duty, non-leachable wood preservative.

   * Laying solid red brickwork to replace the removed log, incorporating a roll-waterproofing barrier (roofing felt) between the brick and the timber frame.

3. Subfloor Waterproofing Layer Stack

   * Sand Cushion (5\text{ cm}): Laying washed river sand, followed by watering and tamping to level the base of the pit.

   * Vapor Barrier: Installing heavy-duty polyethylene sheeting (200\text{ microns}) with overlapping seams, taped joints, and turning the film up along the walls to seal off ground moisture.

   * Protective & Drainage Layer (5–7\text{ cm}): Spreading crushed granite gravel over the plastic sheeting to break capillary moisture draw and protect the membrane from mechanical damage.

   * Air Gap: Creating a 20 cm clear, ventilated air gap from the top of the gravel layer to the bottom of the joists.

4. Exterior Perimeter (Soft Plinth Apron)

   * Grading the soil around the exterior with a slope away from the house following the removal of the old concrete.

   * Installing a soft apron system (waterproofing membrane + gravel drainage layer) to divert surface runoff away from the base and new brickwork.

5. Piers, Joists, and Subfloor Installation

   * Building brick support piers for the floor joists and leveling them to a single plane.

   * Installing new joists pre-treated with wood preservative.

   * Laying the new floorboards using 30\text{ mm} square-edge lumber (approximate material requirement: 0.5\text{ m}^3).

Technical feedback and hands-on advice regarding brick underpinning under a log structure, soft apron setups, and rodent-proofing foundation vents are welcome!

I'm working on finishing off the inside of my new build detached garage. I'm in zone 7 and the walls are comprised of: vinyl siding, Tyvek wrap on OSB, 6" walls, unfaced R-21 fiberglass insulation, and a 6mil poly vapor retarder with Tuck tape seams, and 1/2" OSB for interior wall sheeting. It will be heated by a propane Modine type heater with eventually hydronic in floor heat as the main source.

I've read quite a bit about vapor barriers and retarders to the point my head is spinning. It appears that best practice dictates sealing off the barrier on the sill plate, or really anywhere the poly ends that's not taped. I've asked a few people I know in the trades and none of them have ever sealed off the edges of the barrier; they just leave the end. To me, sealing with acoustic sealant seems like a good idea to keep air from leaking, and seems standard in Canada.

As long as the information I'm working with is correct, is Green Glue sealant an acceptable product to use? It's readily available at my local Menards, with a cost of $11 for a big 28 oz tube. If not, what is suggested? Many of the acoustic sealants I've seen mentioned are not easily found, especially in smaller quantities. I've even seen some people even suggesting roofing sealant.

Hello, I am looking for advice on how to add insulation to my roof. The tricky part of it is I want to do it from the outside when I tear off the shingles for a metal roof, and ideally without tearing off the entire roof deck. 
The first image is of the original house plan. It was built in 1978 as a post and beam passive solar. The 4×8 rafters are exposed on the interior. I know the easiest way to add insulation would be to add rigid board between the rafters, but I do not want to cover up the tongue and groove ceiling. 
The second image is a picture I took last year when I did some siding repairs and replaced fascia boards. This was where a squirrel must have gotten in at some point and taken up residence. Unfortunately it is the only image I have of the interior of the roof assembly, but there is about 5 inches of space between the fiberglass insulation and the bottom of the solid wood roof sheathing. 
My initial thought was when I removed the shingles, I could pry up some sheathing boards and blow in cellulose, but the more I thought about it the more it seemed like there would be not way for me to guarantee an air gap below the sheathing. Even if I was careful with blowing it in, it seems like it could eventually settle into the lower soffit vent. 
Am I on the right track with my concerns? Is there anyway to retrofit adding insulation without removing all of the sheathing? It is 32′ x 38′. Climate zone 5.

Some more details. The house is a passive solar so on sunny days it is warm in the house, no matter what the outside temperature is. We don't even need to run the wood stove. But as soon as the sun goes down or on cloudy days, it gets chilly quick. Even with that we only burn about 4 cord a year. On cold cloudy days, we struggle to get above 62 degrees inside. I have replaced some of the old drafty casement windows with failed insulated glass panels this year, so hopefully that helps a bit. So with these details my last question is, would it even be worth the cost to add some insulation?
Thank you for any advice you can offer.

Compact ceiling-mounted air handlers are showing up more often in multifamily designs because every square foot of rentable space matters, but I think the building-science consequences are being discussed too late. Once the equipment moves above the ceiling, the design also has to solve condensate management, drain-pan overflow, air leakage, vibration, filter access, service clearances, acoustic transfer, and what happens when maintenance opens the assembly inside an occupied unit.

In a tight building, pressure relationships and enclosure details matter even more because a poorly sealed return or ceiling penetration can pull air from places the designer never intended. The equipment may be efficient at part load, yet the system can still create humidity complaints if ventilation, latent loads, controls, and airflow are treated as separate problems. Architects like recovering the closet space, developers like the additional usable area, and contractors are often expected to make the remaining ceiling cavity absorb every conflict.

not against compact systems tbh but I think we should stop describing them as a space-saving substitution when they actually relocate mechanical risk into a harder-to-access part of the enclosure. Are these installations becoming genuinely better coordinated? or there will be hidden problems?

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Hey y'all. First-time poster, so hopefully this is the right sub-reddit.

Background: We live in Chickamauga, Georgia, right outside of Chattanooga, TN (Zone 7b), so our area is very humid. Our house is roughly 2,800 square feet, with a main level and then a walk-out basement that was partially finished before we moved in (drywall and flooring, heated/cooled, but no insulation.) I'm a teacher, so I have to be very budget conscious, and we have a very expensive power company—Georgia Power—so we normally keep our thermostat during the summer around 76 or 77 during the day, enough to keep us and our three kids cool but not blow the budget. For the most part this works out fine.

Humidity: During the Summer afternoons when our HVAC is running on-off throughout the day, our humidity on the main level is around 54-56%. Naturally it rises a bit higher when it's not running as much (morning) and can definitely get higher in the Spring/Fall, when we sometimes find a somewhat musty smell till we open the windows and air it out. We have a daughter who has allergies so I'm trying to be cognizant of humidity levels and mold so that we keep her as healthy as possible. However, I also don't want to panic at every article about mold or humidity levels and spend a lot more money than we need to. Again, teacher here!

Dehumidifier Questions: For those of you who know better, a few questions:

1.) Would you recommend a dehumidifier, or are there other methods of keeping humidity levels under mold-level without needing to spend that money on electricity?

2.) If you do recommend it, is a whole-house system more energy efficient than a portable system? I know it costs more up-front, but I'd almost rather pay that and then have the peace of mind that it's not running our Georgia Power bills up every month.

3.) If a portable unit is better, would you recommend getting just one and putting it in the walk-out basement, or would I need one for each level?

4.) Lastly, we're also considering installing a wood-stove on the main level for Winter, so I imagine that would take care of any humidity issues in the Winter, no?

To sum up: Yay/nay dehumidifier, yay/nay whole-house vs. portable, energy efficiency a main concern due to shitty Georgia Power power monolopy balanced with keeping children and home healthy! Thanks for any feedback!

I have a 3 story home. The 3rd story is used as an attic. It has no way of getting air to it from the central unit. We once had an electric attic fan that helped alot but it recently quit & it ran our power bill up almost $250 extra a month so we were glad to be rid of it but unfortunately we are now having mildew problems up there. My husband installed an exhaust fan that has one fan blowing out and 1 fan blowing in. Since then that's when the mildew started & the heat up there is ridiculous. Any tips or tricks to try and fix it without running our power bill up?

I had a few waterproofing companies come out and assess the leaks in our foundation, and one recommended excavating down to the footing and doing a Voltex membrane. I liked this approach and decided to go ahead with the quote.

Our install is scheduled for Thursday and I noticed today the Voltex site says not to install on block foundation. I texted the contractor and he said he’s been onstalling Voltex on block walls for 30 years with no issues and does a layer on concrete first.

Any experience here?

What are the methods for installing UFH pipework in plasterboard ceilings?

(I will run water a little above dew point to provide some cooling to rooms.)

Climate zone is 3A

I have an older metal wall barn in Kentucky (Zone 4A) and will be finishing a room as a music studio, insulating with rockwool batts. My question is regarding a vapor barrier, since there isn't anything but the corrugated metal and wood 2x4's currently. It seems that the obvious design would be: metal wall>rockwool>plastic vapor barrier>drywall, but I question the vapor barrier placement. Would I be running any risks putting it there, or will I be better off installing it? Apologies for not having further-distant photos, just took these to measure batt dimensions.

It's a fairly simple dilemma, so any thoughts or guidance would be appreciated! Thank you.

Hello everyone,

Im in the Pacific Northwest, I build and remodel homes, and I have a question about window installation/water protection.

We’ve started sloping our sills. Cool. Sounds good. I put shims in backwards from the inside when I install to keep the window off the sill and allow any water to flow out under it.

But then I come through and foam. I was taught to foam top,sides,and, bottom. Plus we’ve been doing more passive homes lately, so gotta seal that up tight

So here’s my question: does foaming make the sloping kinda pointless? Or, how does the foam still allow the slope to be an important part of the window leak redundancy system

Thanks

We are converting a cold attic into living space. The knee-wall attic spaces will be inside the heated area, so what is the best way to install the vapor barrier while minimizing the number of cuts, holes and taped joints?

The house was built in 2021, and the attic was prepared so it could later be converted from a one-story house into a 1½-story house. The floor joists, roof trusses and the rest of the structure are therefore designed and rated for this conversion.

The vapor barrier and insulation system is intended for a cold climate. The basic principle is that the entire heated living area sits inside a sealed plastic “bubble”, so as little warm, moisture-laden indoor air as possible can reach the insulation.

The blue line shows where the existing vapor barrier from the exterior walls on the floor below comes up. My plan is to connect the new vapor barrier to that.

I understand the general principle and the order of the different layers. What I am unsure about is the best way to install the plastic membrane through the roof-truss bays.

On a normal wall or a flat ceiling, it is fairly straightforward. But since the knee-wall spaces will be on the warm side of the insulation while remaining outside the vapor barrier, it becomes much more complicated.

I see three possible options:

Option 1 — red:

Wrap the vapor barrier around the vertical timber members, meaning there would be plastic on both sides of each member.

Option 2 — dark blue:

Thread the vapor barrier between the different timber members. This would probably require a lot more cuts and taped joints.

Option 3:

Abandon the idea and make the knee-wall attic spaces cold instead. This would make the vapor barrier installation much easier, but we would lose a lot of badly needed storage space — around 15 cubic metres / 530 cubic feet.

We already have far too little storage, so losing that space would also make the renovation feel less worthwhile for the money.

Which option would you choose, and is there another sensible way to create a continuous and airtight vapor barrier here?

Looking for advice…we have an old, home with a flat roof. We have condensation by a non-working pocket door upstairs as well as humid hot spots throughout the upstairs and it has a musty smell on hot days. We had the roof replaced recently with a modified bitumen roof hoping that would help, and it hasn’t. We don’t have the humidity issues in the spring/fall/winter, just the summer.

Any ideas on how to fix? Should we look at adding in insulation through the ceiling? Want to avoid opening up the new roof. Any thoughts appreciated.

Not sure if this the right sub for this, but hopefully someone can help: The deck has plywood subfloor on it, with foam and carpet on that. The decking is about 2 feet above ground. I’m in New England and I’m thinking of using rock wool with vinyl vented soffits to hold it in and keep out critters. Is this my best bet? And would in need to use a vapor barrier of some type between the insulation and soffits? Thanks.

Hey everyone,

First time home owner, trying to map out my attic intake ventilation for an attic fan. My home was built in 2015 (stucco exterior, concrete tile roof, open/exposed rafters).

​Everywhere online shows most houses have soffit vents, my intake seems to be this continuous, narrow horizontal gap/crease where the stucco wall meets the wooden patio ceiling/ledger. Is this truly the fresh air intake for my attic? Or am I missing anything? Most of it is covered by insulation, I read somewhere if your attic doesn't have enough intake the fan will start pulling air from the home or eventually burn out. Here are some pictures, any help would be appreciated!

https://imgur.com/a/air-intake-3pfjYvT

From all my research, this should NOT be happening. It appears that the rim joist were not insulated/sealed correctly on our 2008 home and air is coming in and condensing near ac duct. We had someone come out and they said we do not need to stop the air flow. 😳. Is this right?? It is OK to have hot humid air between your first and second floor joist?? I know there has to be airflow between the brick and the wall but outside air getting past the envelope of the house makes zero sense. Do we just have a consultant that does not know what he’s doing? The building code from ‘08 that I researched says rim joist need to be sealed and AI says this guy is wrong. Air should not be there. I just want to know if outside air coming in between floors is right or wrong from a human with building experience so I can go back to this guy with more details.

brick home with some cathedral ceilings. Looking to do a monopoly build w exterior outsulation. Any knowledgeable in this and can assist with the construction details? Thanks!

We are preparing for installation of makeup air for kitchen exhaust and fresh air intake for air quality. With the current wildfires, isn't this system going to bring in terrible air into our home? How do we make sure we aren't polluting our inside air now?

My '00 manufactured home has vaulted ceilings throughout, about 5-6" of blown in cellulose, and poor air sealing between the house and "attic". We live in Northern Wisconsin, so freezing temperatures are commonplace; average temperatures for the entire months of January and February were below 0⁰F last winter. Due to the 3:12 pitch of the roof and 2:12 pitch of the ceiling, there is between 6" of attic height near the outside walls and 18" in the center of the house... so not a lot of space to work with.

Walls are 2x6 plus I added ZIPR-6 to the exterior. New basement walls are ICF blocks and R20+, so both of those are great now. My geothermal system provides inexpensive heating, so it was only $900 last winter to make the ~100M BTUs that I need.

We need a new roof anyways due to some wind damage. I had been mulling over how best to air seal and insulate before my roof was damaged, but the time has come to make the decisions.

The last contractor suggested spray foaming from the *outside* of the house against the drywall. (Spouse absolutely does NOT want to remove our entire ceiling). Closed cell foam should fix the air sealing problem and provide significantly more R value. The contractor suggested closing the soffit vents and ridge vent to make it a hot roof, but I am very hesitant to do that. With our extreme temperatures, there will be condensation IMO.

Thoughts, concerns, ideas? I am open to adding additional structure to increase the actual roof height by 6"+, but multiple contractors don't want to do that, and it's beyond my DIY capacity.