Hill House Forms

Designed for Black Dike home, to be used in future homes.

After my experimentation with various forming and pouring methods, I finally settled on this as the best procedure for wall-forming.  It uses preformed steel joists as forms, pouring is one lift of 5" to 15" per lift, and will work for most buildings.  The forms can be placed easily enough by 2 workers with little expertise.  With reasonable care care in form-setting and vibrating, should deliver a clean wall.

I'm showing a deep footing here, because the site on Black Dike dropped off at the South/Rear, and the cooling tunnels enter low thru the back wall.  I went to bedrock, which was as much as 7 feet below floor level.

Stepped footings 8-11" thick rest on bedrock all the way around, using 2 #4 horizontal rebars for reinforcement, and with #4 vertical rebar at all corners, beside all openings, and 4 feet o/c to fill in.  Because of the height of my back foundation wall, I put in some extra vertical rebar.

Additional rebar should be placed horizontally in the wall at the floor-level layer and at least every 4 feet.

The forms (shown blue on the top course ready for pouring) are placed horizontally on the footing, and held in place with plywood slip-collars. 

This  pic is a thumbnail.  Clicking it will open a large image in a new window.   It will prove an advantage while reading this page!

 If too-lightweight gauge is used, the forms will be flimsy to handle, and will require extra slip-collars & perhaps wedges between the slip-collar and the form web.  Since you're only buying only enough form material to pour a single lift of a few inches, skimping on form stock is a bad idea!

For the Hilltop House we're using 10" high forms to pour prox 8-1/2" lifts.  The spare inch just barely avoids having to battle the rounded corners of the form stock, which would result in bad-looking surfaces!  A few self-drilling sheet metal screws are placed thru the form above the bottom edge curve, resting upon the "yesterday's concrete" below, being simply raised and reset for the each lift. 

To prevent damage to the concrete, the screws should be backed out to remove the forms, then replaced when resetting forms for the next layer.

Strong form collars are important, 5/8" or 3/4" plywood placed every few feet over the sideforms, cut accurately to press the lower edge of the forms against the concrete below.

A rechargeable 3/8" drill with magnetic screwdriver bit is almost indispensable in all phases of this type building!  A skilsaw with metal-cutting blade will be about the only other tool needed.

Ordinary Durowall-type wire masonry reinforcement should be used to tie the inner/outer concrete together.  This is laid atop "yesterdays" concrete layer before the forms are set.  It's not necessary every layer - but that's another design/engineering thing - part of the many details in my designs.

I recommend the wall insulation extend well below the floor-line.  Keep the bad out and the good in. 

First preparatory step is to level and smooth the dirt below the floor.  I have a BUNCH of checking and testing to do, but I hope that it will work to place a layer of rigid foam on the dirt to stop the downward heatloss.  Compression and settling are the big issues here.  Then a layer of plastic sheeting, then a layer of washed rock (bigger is probably better, but anything bigger than 1"-minus gets really hard to level!), and finally the poured floor.  There are many little detail issues one should address regarding perimeter insulation, also.  Yes, there is an insulation gap between the floor edge and the wall foam-board! 

Whenever I settle on the floor I'll do another, separate, webpage here and discuss this in more depth.  Meanwhile, I'd love to hear by eMail from anyone with input about this floor insulation biz and alternative ideas!

 Permission is granted and welcomed for personal application only.