FPSF / Discussions

Building in WY area Zone 4b. I would like to build a Slab on Grade foundation. Reinforced concrete perimeter footings approximately 12" x 40" deep, and a 4" thick concrete slab on top of 2" rigid insulation. This will be a monolithic pour. The top of slab will be approx 12" above the soil. I plan to isulate the outside...

I am in the early stages of planning a new home build. Am I correct in assuming that slab on grade constuction with passive floor heating would rule out the use of a heat pump. Also I would question your depiction of crawl spaces as damp and moldy. In a previous house I built with ICF walls the crawlspace was warm and ...

Will I get the benefit of thermal mass with a foundation where the inside of the foundation stem walls are insulated and the rest of the horizontal part of the foundation is foam insulation mon on the bottom followed by 4" of AB topped with 5" of concrete? From what you describe above, no, your stem walls will not offe...

Can you use slab on grade for a 20 by 14 room extension on a main house with Poured concrete dirt floor crawl space.  Yes, you can pour a slab on grade as a frost protected shallow foundation directly adjacent to a house with an existing foundation. You would need to have it properly engineered of course a good possibl...

I am looking to put in a 24X36 Post and Beam Garage/Workshop, assuming the post are mounted on a concrete pillar below the frost line, how would you integrate the Slab on grade with that construction? There isn’t a case where we would suggest going below the frost line with frost walls for a slab on grade, we prefer to...

I'm building a shop (~950 sq ft) and a cabin (~800 sq ft). They are on Manitoulin island and will be on exposed flat limestone that is randomly segmented. I will be getting the assistance from an engineer, but would like to be somewhat educated and know my options before working with them  or the building inspector. I ...

I am planning on building a small house 35 x30 that will sit on a slab on grade. I'm planning on installing some kind of wood floor so my question is. Would it make any sense to install rigid insulation between 2x3 every 12 inches and cut down on the amount of insulation under the slab? Also, how do feel about using th...

Hi, Planning a home in rural Southern Ontario (Zone 6A). We want heated slab on grade but are concerned about preventing seasonal issues in winter. Legalett systems look very good especially their air radiant system. The question for us is what happens in winter when we are away for a few weeks? We'd need to keep heat ...

...FPSF., 8 inches Rockwool rigid board under the exterior of the slab, Tpye III EPS foam under footings  and a skirt of R8 insulation extending out 4 feet.  ARe these suitable for such conditions.  Have these materials been tested to see if they retain their insulating properties over time??   If not, the concrete slab w...

How would you determine the thickness for a new construction of a slab on grade that will have only liquid forces acting down on it? Not sure what you mean by liquid forces, but a slab will perform differently depending many issues such as soil quality and bearing capacity. Slabs are most often edge loaded (where the l...

Hey.  I have a question nobody seems to be able to answer: We're building an 1100 sqft ranch on a monolithic slab w/ 2" hard foam insulation under slab (+ crushed stone & eps vapor barrier), and 2" hard foam insulation vertically around sides/edges of slab and subfloor above.  On top of the slab will be a wood subf...

We are planning a build for June 2020 in Prince Edward County, Ontario where there is 1 ft of topsoil, 2 ft of clay and then bedrock.  Structure planned is a bungalow of ~ 2000 sq ft with a 3 car attached garage.  Based on the promotional material, the Legalett system seems like a good choice to avoid sump pump and opt...

We're soon building a slab on grade foundation for our new cabin in Montana and I've decided to sit it on a 4" EPS foam insulation so the slab will retain some passive solar heat from the south facing windows in winter, avoiding having to put too much heat in to keep stuff from freezing. There's a bed of compacted grav...

I'm building a home up north in Parry Sound, Ontario next year. I'd like a slab foundation raised three feet above the ground level. I'd like to have a wrap around porch.  So aesthetically I think it looks better than being on ground level. As well because of snow accumulation.  My question is what would be the best wa...

Allergic to chemically treated wood, CODE requires PWF on concreted slab before house can be built Where are you building where code says such a thing? I don't think I really understand the question so I would need more information. A pressure-treated wood foundation (PWF) would be an alternative to a concrete foundati...

...FPSF in Southern Vermont (AFI 2300).  I want to fully insulate the radiant slab by including 4″ XPS under the footings but this seems to conflict with the FPSF principle of relying on heat transferring through the footing to stabilize the ground temp.  My next thought was to use the FPSF design guidance for an unheated...

I am looking to build a bungalow in a moderate climate. Temperatures range from about 30 to 65 in the winter and about 45 to 75 in the summer. The house will be south facing with lots of south facing windows with tile and concrete floors. I expect this will produce enough heat to keep the house comfortable with out any...

The grade on the building site drops 8 feet over 72 feet. Is it feasible and cost effective to build three slab foundations that step down in order to deal with the slope. The top foundation would be a for a single story 15 by 24 room. The next level would be a 24 by 24 two story structure and the garage would be at th...