5-Layer Slab System for High Performance Home Build

Home Diagnosis TV series co-host Corbett Lunsford shows the installation of the 5 layers of performance control under his family's new house. Thanks to Royal Building Products, Rockwool Insulation, Stego Industries, and the subcontractors who worked so hard to get this right!

[marcustait]

Loving your philosophy on how you value skilled labour!!!!👏👏👏

[javierluna]

Great video and great advice.

As a residential and industrial contractor, I never deal with customers who haggle.

Quality work cost money and I wont hire crappy subcontractors.

Many customers who didnt hire me because they hired the cheaper guy, have called me back to fix sub standard work.

It costs more to tear down shotty work and redo a project.

Customers always get what they pay for.

[Johnintoit]

Nice to see high performance builds popping up more often, I'm a contractor in Ohio and I am building a Passive house this summer for myself. My only real concern is the Rockwool under slab, I am huge Rockwool fan and will be using it on my build (exterior insulation) but the concern is that while it cannot to be harmed by water it sill has the ability to absorb water given enough contact time and no real way to dry out so it may just be a like a damp sponge, hope for the best there.
Only other thing i would suggest because your in a high Radon area is to use a primer then tape approach when attaching your vapor barrier to the concrete, good luck on the build I look forward to the updates.

[jorgeantelohollweg]

I am enjoying this so much!!!! Keep going Corbett!!

[premiercconstruction]

Challenging soul conditions, high radon area, termites... all tough challenges. Looks like you are doing amazing job. Lots of thought put into project. Probably best foundation in area hands down...

Love rock wool insulation best stuff for sure. Careful that it does not get super wet. Why not put the liner under the rock wool? Also I hear it’s better in walls as well as compared to spray foam which has lots of off gassing and can hide termites and water damage issues....

I always go 4” min on something that big. Also I solute slab from footing wall.

I have to say I’m liking your videos more and more. You are definitely a critical thinker and not out to simply reinvent the wheel. Thanks for sharing... and great treatment to those who are working for you....

[danthesupercontractorhvac]

I appreciate the last comment, I tip my hat to you good sir.

[elliotgold]

I’ll be incorporating some of this into my “budget” high performance cabin. I like 2” slab. I was worried about concrete costs for a 4” slab in the crawl space. You make a good point, it’s not structural.

[terrybrown]

MATT Reisinger and associates all are Great Help

[nicpedia]

I tried talking my concrete sub into doing XPS or EPS foam below slab. He told me I was crazy and that was never done here. Building design needs to improve like this. Great video, going to have to review the other ones of yours.

[DougCube]

How does using Rockwool for the underslab insulation compare to using rigid foam? In my build, I was planning on using EPS for the slab insulation and Rockwool for exterior walls.

[shakejones]

Great Thank you SO MUCH for sharing your knowledge! Well done mate - NEW SUB 🙏🏻

[ABZD]

I was just on the Rockwool site looking at the Comfortboard 110, wondering if it had high enough compressive strength to sit under a foundation footing. The IRC prescriptive code allows foundation design for soils as low as 1500 PSF compressive strength, and at 25% compression Comfortboard 110 is 1566.

I know EPS gets used under footings, but it might even be possible for Rockwool too. It seems like as much insulation is used under a slab or even the foundation wall, the footing becomes the largest thermal bridge. Why not eliminate that bridge entirely if you can?

[sketchapp]

Can you show how you're dealing with the wastewater and plumbing coming out of the crawl space. I'm always at a loss of how to plan for this when I'm thinking about a building. I want to be able to put down a crawlspace first then deal with the plumbing.

[charliexu]

I wish I can see how the radon system & drainage system besides the Form A Drain Part get buried inside the slab. I see a white PVC pipe running horizontally in the middle of the floor area. Is that for radon ?

[Sailoralso]

In northern climes you have an error. Possibly even for Atlanta. The slab you just poured is in contact with (the exception being a 15 mil sheet) with the rail footing and the concrete foundation wall. No. The slab temperature is governed by what it is in contact with. Concrete has an R-value of less than R-1 per FOOT, , maybe. So, , , why did you bother with R-10 under the slab? You will have about an R-2 average yield. Thermal conduction and thermal bridging.

Don't pour a thin slab. Pour a thick slab, the slab can become not an enemy, , but a benefit, , a thermal flywheel for the house. (Cool or heat the slab, , and the house will be cool or warm. Cool with night air, , heat with sun, , both are free.) but, Isolate it from ALL contact with footings, soil, and outside air. If the slab is only in contact with the interior air, it will be the same temp as the interior air.

Fiberglass speeds the set time. Pouring on insulated foam increases the set time. A 2" slab will not generate heat anything like a 4 or 5 inch slab. and a 2" slab on foam should not be walked upon for finishing. Bull float it well and leave it alone. 2" slabs work very well. I would use a higher bag count, which also increases the heat.

In Atlanta, , only try that pour in the winter. At 80F and sun, your set time will be in minutes. In any other than winter, use retardants, or a 12 man crew.

Isolate your slab. And, , the vapour/water barrier goes under the sheet insulation, not over it. The R-value of your insulation is based upon a dry insulation. A rockwool insulation can be wetted . A wet rockwool insulation has no R-value. Rockwool or foam insulation should be on the level above the rail footing, and perimeter isolation band can be accomplished with a burial grade pressure treated 2X4, or 2X6, , , ,or,, high density poly-isocyanurate (uncommon), , or high density urethane foam 3 to 5 pound density works well, or even pumice bricks. (used for cleaning ovens and grills)

My first isolated slab was 1983. I've made lots of mistakes, , no reason you should not benefit from my misdeeds.

[jimmiedow]

You mentioned in your Manual J video that sub slab insulation is "the last thing you do" because the thermal connection with the ground actually helps cool your house in the summer. Did you end up calculating that the heat saved in the winter is worth more than the free cooling in the summer? Is there a situation where you are actually better off by omitting the insulation?

[majala]

Looking forward to seeing the humidity/radon levels. Great job!

[tcranston]

The compression loads are in PSI, not in "pounds per sq foot." You need a min of 25 PSI under the slab to prevent insulation collapse. Roxul will give up to 80 PSI, and most rigid 2" board is above 25 PSI, too.

[Forrest-Jackson]

You had me at "we should be paying people what they're worth."

[stringsandapick]

Looking great! Remember, when you haggle on price, the contractor looses money which does not make them happy, which means sub par work. I typically include a box of doughnuts or a nice BBQ lunch for the crew for crews on occasion, helps break the ice and puts everyone in a god mood.