Chapter 1
The following four pages/chapters provide details on how we build. Each home, location, customer, etc. is different, of course. Our Design Services pages are worth reading as that section contains a great deal of building information. For the those who want even more information (other builders, owner/builders, or just addicted web surfers) our Technical Library contains still more details (mostly a collection from other sources).
At Nutmeg Homes we continually strive for improvement. Most of our building practices remain constant, but if we, or one of our trades can find room for improvement, we will adopt that method / product if we can. Take, for example, the Heat Recovery Ventilator (Fresh Air Filter/Temper Exchange Unit) System. While the venting and distribution has always worked well, after working with several companies we have found FANTECH, a New Brunswick company that provides not only a great core unit - but also very good (and good looking) controls. Hopefully other manufacturers will start including controls that are not cheap looking (we have been nagging some of them).
Footings
Concrete footings with steel reinforcement
Once the 'hole' is dug, down to solid (or bearing) ground, footings are poured. Footings for ICF walls are typically slightly larger than those of wood buildings due to the weight of the walls, especially multiple story structures. The footings have vertical or upright steel at regular intervals. The vertical steel in the footings will then connect with the vertical steel in the walls (connected means an engineer specified overlap).
Three
layers of blocks on footings
The first row of ICFs are set on the footings and temporarily spot glued. The straight ICF blocks, usually 4 feet long, and the corner blocks all interlock. Each row gets one layer of steel reinforcement. The next row 'clicks' (a locking tab or bump - just like 'leggo blocks') on top of the row below. A block is generally 16 inches high and we just keep adding layers until we get the desired height. For tall walls or multi-stories the concrete is poured/pumped in every 8 to 10 feet in height.
Basement / Crawlspace
Filling the steel reinforced walls with
concrete
The pumper operator (that's Casy in this picture) uses a remote control box to move the 'boom' and concrete is poured inside the ICF's (Darryl is guiding the hose). At Nutmeg Homes we general increase the 'plasticity' or 'flowableness' of the concrete by adding more cement to the mix. 20 mpa is the design minimum and we usually increase this to 28 mpa. Then the concrete is 'consolidated' using a concrete vibrator (that's Kyle with the vibrator - Darryl's bother) to insure there are no 'air pockets' or voids.
NUDURA Corporation is now carrying the new innovative Multi Purpose Anchor / Hanger System. This product is the newest concrete embed system designed for the ICF industry. The functionality of this product lends its use to hanging floor joists, roof systems, exterior deck installations, as well as anchoring or fastening an interior or exterior applied frame partition to an ICF wall. Easy to work with and extremely cost effective, it saves both time and money in a standard installation. Nudura Web Site (the Best ICF .. imho)
Floor joists
attached to steel hangers embedded in ICF wall
Once the basement or crawl space is poured the floor is installed. We like to use a Canadian invented system (ICF's themselves are a Canadian invention too!) called 'ICF Connect' each floor truss is attached to two steel plates that are embedded into the concrete wall (plates are inserted before the pour). We have found this hanger system to be easier, faster, less expensive and likely stronger than the 'old' system (the ledger brackets or embedded bolt systems).
Main Floor
The next floor is build and ready to pour
concrete
The main floor walls are just a repeat of the previous step. Vertical steel overlaps connect each pour. Horizontal steel is placed in each layer. The usual rule is to have 10mm rebar every 16 inches vertically and horizontally. This results in an interior steel grid of 1/2 inch reinforcing steel in 16 inch squares throughout the entire structure, typically about 5 tons of steel per home! ICF structures are fairly solid even before the concrete is poured!! Paul and Shareen pictured here are the hands on owners of Nutmeg Homes.
Scaffold
and bracing removed
After pumping in the concrete for the main level, the bracing from the walls, windows, doors, etc. is unscrewed. Now we proceed 'as usual'. Wood stud interior walls and roof system are standard frame building practices. The next notable difference in a standard Nutmeg Home is our interior climate control systems. Shareen keeps a clean and tidy work site.
Radiant Heat - Hot Water Lines
I think the best heating system in the world is radiant heat. It's the most even, comfortable form of heat because it works by actually heating the floors, walls, and objects in the room, rather than by just blowing warm air over them. Radiant heating systems can also be among the most efficient. Mike Holmes
Radiant hot
water 'pex' lines layed out
Here the pex lines are layed out using a predetermined spacing schedule. The underside of the wood floor is insulated so the heat radiate upwards. Layout of the lines is a skill best left to professionals. More/closer lines are layed out under windows and exterior doors. Often several 'loops' are needed for a large room or area. A skilled radiant heat installer will usually layout the lines so that 'area within area' control can be achieved. For example in a hallway and bathroom set up on one zone but two loops, the valve manifold for each loop can be adjusted to keep the bathroom warmer than the hallway - using only one thermostat for that area.
There is 1 1/2" of concrete encasing and covering hot
water lines
Steve and Kyle spread 1 1/2 inches of concrete over the hot water pex lines. This not only protects the lines, but also helps distribute the radiated heat more evenly. An average home will use about 10 tons of concrete for the floor base. Once all that concrete has warmed up to the required temperature, it takes very little to maintain an even temperature. Another benefit of a well designed hydronic radiant system is the even temperature achieved. Very little fluctuation in temperature happens with this system, no noticeable cold/warm cycles, no 'cold spots' in the rooms.
About 10 tons of concrete per floor - THAT'S thermal
mass!
In the winter, once the floor is warm, the furniture is warm, then the walls warm. Here's the best part of radiant heat in an ICF structure. Sure 10 tons of warm concrete floors are great; and efficient; and comfortable, but when the exterior walls become part of the 'thermal mass' - WOW! An average Nutmeg Home has about 400 TONS of reinforced, double insulated concrete as a exterior shell. Heat loss is now only through windows, doors and the ceiling. The walls literally keep the house warm in the winter and cool in the summer. Quiet and Comfort are the most cited benefit of an ICF home.
Next - the Windows, Doors, HRV and Zone Controls
>>> Chapter 2