Home Addition

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Posted by: from Coaticook
2/24/2013 at 1:57:55 PM

We are planning a home addition (living room) of 16 x 20. We had an estimate done with a full basement finish for a bedroom. Since it is over our budget and we do not need the additional bedroom, we were looking for an estimate of the savings for the same addition on screw piles.

Also, what kind of insulation is needed for the floor of such addition and how do we put the duct work?


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Date/Time2/24/2013 at 4:42:20 PM

Your addition needs to be built on concrete piles and a grade beam. With the crawl space to be insulated, the crawl space floor needs to have a sump pit and concrete floor.

Not sure of the extent of work to tie into your house, and you will need an engineered plan.

You would be looking at a minimum of 75g where I live.

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Date/Time2/24/2013 at 4:58:27 PM

You need to put in a 2 layered floor system, 1 set of joists running in one direction, and the second layer of joists running in the opposite direction.

Your lower layer system gets spray foam insulation, your upper layer gets the duct work, as any other floor in your house.

Footing and piers under all this support the structure and the rest of the addition gets erected as normal building construction

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Date/Time2/24/2013 at 5:02:30 PM

Hi there,

Without knowing what you were quoted, where you are or the details of construction it is difficult to say what the savings would be, but they would be considerable, somewhere in the 30% range I suspect.

Spray foaming the floor system is the best way to go in this case, providing an air barrier, superior insulation value, and less difficulty with mice, squirrels and insects. You should still enclose the area from below none the less, especially if you are somewhere that has porcupines, they love the stuff.

Good luck

Rob Jackson


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Dolphin Construction Co. in Ottawa
Date/Time2/24/2013 at 7:01:28 PM

If you hade an estimate done with full basement go back to the same guy and ask him for a price without a basement.

Good luck with your project.

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Date/Time2/26/2013 at 1:59:17 PM


In general, you would be looking at approximately $200.00 a square foot to realise this project.

As for heating system, I recommend that you would go with electrical baseboards. Thus, eliminating the duct work problem and cost.

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Shannon from Panoramik Design Build in Ottawa
Date/Time2/26/2013 at 11:17:27 PM

Hello Mark,

By using the system you are asking about for the footings you will save a bundle.

Unfortunatly there are a few limitations with this product. Soil conditions is the major issue. If the soil is too rocky or different types of clay they can not be used. Contact a local dealer in your area and they will tell you if it will work for your project.

Good luck,

Jeff Picard

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