The Hole

What gets Bigger the more you take Away from it?

Whats Holding Your House Up? The Footings

building excavationFooting forms ready for concrete

There are 3 options for the base of a house; basement, crawlspace and slab. But first you’ll need footings. Footings must be on ‘bearing ground’, that is firm undisturbed ground free of organic material. The goal here is to provide a base that will not move, shift or deteriorate (organic material ie. tree roots will rot and create voids) over time. Getting good ground to build on involves removing the top ‘overburden’ of soil, plants, trees and their root systems at a minimum. You may need to have a ‘geotechnical engineer’ involved if the bearing ground of your lot is in any way suspect. The footings should be wide enough to distribute the weight of the structure. Footings should be steel reinforced, this is an inexpensive step that is easy to do (but may not be required by code).
With ICF structures of 1 or more stories the footings will likely need to be a bit larger than code minimum, and should be as level as possible. The drainage system around the footings is critical – keeping the underground water flow away from the footings insures that there will be no undermining and therefore weakening of the structural integrity of the footing to bearing ground support.

Slab, Crawl or Basement

acid stain floorsShaped and acid stained slab

A slab – a concrete slab at ground level or slightly above ground level, is usually the least expensive option. The bearing ground should be just below the original grade (original ground level), if going deeper to hit bearing ground is required, consider a crawlspace – especially as ICF is already insulated! There is a point where it is cheaper to build a crawlspace and frame the floor than it is to fill in and compact with good clean fill, the required base for a floor slab. Floor slabs should be insulated underneath, this may not be required by code, the code is not about comfort. At Nutmeg Homes we have done several insulated on grade slabs with radiant hot water lines to heat the entire slab in zones, and rather than being hard and cold, these floors are warm and comfortable (and beautiful too!). Nutmeg Homes proudly specializes in a wide variety of beautifully finished heated concrete floors, see Nutmeg Floors division for more.

ICF basementICF basement insulated, ready for drywall

Crawlspaces make not only good storage areas, but also make running utilities like plumbing, venting etc. much easier. If you end up with a crawl space with 5 feet of head room or more, then digging a bit deeper (if possible) and going to a full basement is strongly recommended. With traditional basement construction temporary wood forms are filled with concrete, stripped, and the basement interior walls will be cold, bare concrete. No matter what how well you insulate this type of wall, you now have exposed concrete in contact with air, and in a rainforest climate this means very moist air will contact cold concrete and condense. This is why basements often have that special smell (mold, rot and moisture). If you seal the entire concrete interior face with EPS foam insulation boards, you will improve the situation, and even better, do the same on the exterior wall to temper the temperature of the concrete mass, you can then achieve a dry warm basement. OH … WAIT A MINUTE … ‘EPS – Concrete – EPS’, hey that’s like an ICF wall!

dimplemembraneSuperseal Dimple Membrane System

We waterproof with a dimple membrane system all below grade walls (not damp-proof, not code minimum which is a thin paint or spray on layer of tar stuff on bare concrete) . This is not required, but since a Nutmeg Home is going to be around for many hundreds of years, we do it right the first time. Building a basement with Insulated Concrete Form (ICF) is a ‘no brainer’. Many times we at Nutmeg Homes have been told by people who have ICF basements how warm and comfortable they are, and usually this is followed by “we really regret not making our house walls ICF as well, our basement is more comfortable than our main floor’”.

grade entryGrade entry, stamped concrete

Since an ICF wall is a continuous shell from footings to roof, the interior floor system can be anywhere the customer desires. We encourage our customers to have the main floor slightly above the original grade and then slope the back-fill up to that level. This is called a ‘grade entry’ home and it makes access for moving much easier and is also now completely wheel-chair accessible. Some customers may prefer attractive steps for the front entry – no problem, there is no concrete wall to wood shell issues to deal with.

The ‘Hole’ stage of construction can be muddy and dirty, so it’s nice to be done that stage – back-fill and move on to the next phase …

Chapter Two – Part 1 – The Shell