Installing exterior insualtion

I will be building addition for my old house and replacing siding. I am leaning towards fiber cement or cedar siding. My house currently has no house wrap. I want to install exterior foam insulation boards over entire house and new addition. I have a couple of questions.

  1. Since exterior foam insulation boards are 1" to 2" thick what to do with windows? How to make them flush taking into account increased wall thickness due to insulation? Right now they are flush with sheeting.

  1. Can someone point me to info regarding what goes over what: house wrap, insulation, rain screen and finally siding?

Reply to
ls02
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Build up with boards thicker than final surface of new siding.

House wrap, thin foam panels, vinyl siding, done. Windows and door openings flashed as recommended after house wrap. Go poke around some new construction sites after working hours and view what the journeymen are doing. Don't overcomplicate your own project.

Joe

Reply to
Joe

There is usually a stand off between window edges and exterior surfaces - meaning that you build up the window edgeing and then trim it. If this is the trim that you will paint you would buy brick mould. If you are going to wrap the trim in aluminum just custom mill the needed stock yourself and save the cost of moulding. Who cares what's under the aluminum.

Reply to
C & E

The current issue of Journal of Light Construction (Nov 2009) has a good article on Retrofitting Exterior Insulation.

If you are thinking of replacing your windows at some point, this would be a good time. You could decide to set the new windows flush with the outside and add internal jamb extensions, or flush with inside and add exterior jamb extensions. If your windows are OK, then you will have to add exterior jamb extensions (and head and sill extensions) to make up for the foam thickness. You'll want to flash the jamb extensions. Make sure to maintain the sill slope with the extension.

Put the house wrap on first, then the foam, taping all the joints with the proper tape. It would be ideal to use two layers of 1" foam staggering the joints, but that's more work and will cost more than 1 layer of 2". Then put vertical nailers for the siding, screwing them into studs with long screws. The foam will serve nicely as the rain screen. Fiber cement is heavy, so secure the nailers well.

Along the bottom edge, put a strip of ridge vent material (the woven plastic kind) wrapped with window screen material. This will block off the space behind the first course of siding while allowing water out and keeping critters and insects out.

Good luck!

Paul F.

Reply to
Paul Franklin

Thank you for thr info. I replaced windows a couple of years ago. They are top quality casement windows installed now flushed with sheeting. I don't want to rip and re-install them.

I assume by "vertical nailers" you mean wood strips to nail siding to? How thick are hey to be? What material are they made of? If they are fur or other wood can they rotten with time?

Reply to
ls02

Yes, wood strips. Typically 1x3 or 1x4 laid flat. They shouldn't get wet enough or stay wet long enough, to rot.

Paul F.

Reply to
Paul Franklin

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