Information about design and construction of earth sheltered homes and a journal of my own progress

Installing QuadDeck ICFs for the Mezzanine Roof

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Posted on October 10, 2018 by

I wanted to experiment with flat roof structures also, and it seemed like the best way to do that would be with the Quad Deck panels (we also used these to cover the basement).  This is some explanation of how we did that.

First, the video.

The Video

 

The Basics

Quad deck is fancy formwork (Insulated Concrete Formwork, AKA ICFs) for pouring a concrete slab over an open space.  To increase strength of the final concrete structure, Quad deck shapes the concrete into Ibeams.  It also includes its own internal steel structure to help it resist deflection before the concrete cures.  The EPS (expanded polystyrene) foam is the tough 25 PSI stuff.

When installing, there are a few key concepts to be aware of.

First, you need to support the weight of wet concrete until it cures.  This means you will need secure shoring.  The brochures show fancy specialized equipment, but scaffolding and cross beams works also.  These need to be strong, so do a little math and make sure that your shoring can handle the load.

Second, the concrete is going to try and push the ICFs apart.  If it can separate them, it will just spill thru between them and you will have a huge mess.  Toe nailing screws thru the shoring cross beams and into the steel reinforcement in the ICFs can prevent them from moving apart.  The “experts” who installed my basement used drywall screws.  I had a much easier time using self tapping metal screws that could easily tap into the steel reinforcement in the Quad Deck.

Third, don’t forget you will need to remove the shoring later 😉  The guys who did my basement often put screws in at angles that were only possible if the Quad Deck wasn’t there.  That gave me quite a hassle.  Build your shoring from below so that it can be removed from below.

Fourth, keep in mind that the concrete needs to sit on the perimeter ledge.  You will be removing that shoring, so the concrete needs to be firmly distributing its weight on the ledge around the perimeter.  This means you need to remove all the insulation from the edge of the QuadDeck panels.  It is tempting to leave some and let the ICF overlap the edge a little, but every bit of the ledge covered by the ICF is a bit of the ledge not supporting the load.

Fifth, you will need to mind the gap.  After installing the quad deck.  you can use spray foam insulation to close up any gaps between the wall and the quad deck.  Remember from 4 that we don’t want any insulation on the ledge.

Sixth, following your rebar specs, and especially rebar for the bond beam around the perimeter, is critical for strength.  Concrete is terrible in tension, you need the rebar for any sort of flat floor to carry a load because that load inevitably creates tension, especially in the bottom of the Ibeams.

Seventh, this is a pour, so close all the sides…  Also, make sure that the perimeter wall is to the correct height for easy finishing, etc.  Don’t just mark the wall where they should fill to, trim it off if you can.

Maybe I’ll come back and add more later.

The Gallery

A pic is worth a thousand words and here are a bunch of pics.

Building the forms for the radial vaults

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Posted on August 13, 2018 by

In preparation for shooting the gunnite on the roof we needed to put up some forms that would keep the concrete from just falling thru.  The radial vaults have simple curvature, so we could build the forms from boards pressed up against the steel arches.  Making that happen took some compromises in the plan.  As usual, challenges arose.  Enjoy.

The Video


The Chimney

In the video I forgot to include any footage of the chimney going in.  Basically, I built this form so the shotcrete would create a good base for my chimney on the vault.  My one regret was that I didn’t think to close the top of the form in order to prevent the gunnite from going inside the chimney hole.


The Gallery

A picture is worth a thousand words and here a bunch of pictures

XPS gunite formwork for the south wall

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Posted on July 14, 2018 by

In this segment, we formed the south wall for gunite.  The video, details and pictures can be found below.

The Video


Details

Order of the layers

We had formed previous shotcrete walls with steel studs and lath and steel studs with XPS insulation.  We liked the idea of combining the insulation in the form because it saved us the step of attaching it, however, the steel studs caused “void shadows” in the shotcrete and water could travel thru those voids, etc.

For this south wall, we decided to use the steel studs to form the XPS, but we would put the shotcrete outside the insulation, on the opposite side from the steel studs.  We could then use just a single layer of XPS and then backfill between the Studs later to increase our R value.

If this were a load bearing wall that needed to incorporate rebar in the shotcrete, we may have come up with a different idea.

Curved Bucks

To make the curved bucks, I used CAD software to figure out the size and angles of the little wood blocks, making sure that the longest side was something easily measurable on a straight edge.  In this case, I used a 5 inch length (4.999 is close enough to 5) and an angle.  I setup the miter saw with a stop block so I wouldn’t have to measure each one.  Then I would just need to flip the wood board for each cut so the blocks came out with the right trapezoid shape to assemble into the circle.

Gallery

A picture is often the best way to tell a story, so here are a bunch of them.