Thermocore notes that their panels that don't require jamb extensions.

I know that it would add cost, but I have no idea how significant the cost difference would be.  How much additional cost is there to add jamb extensions?  (As a basis for a WAG, assume a 2400 sf house with 16 windows and three doors.)

Other than jamb extensions, would there be any other costs that would be required with thicker walls?

Thanks for any comments you can offer.

Larry

Be aware that only Thermocore's timberpanel (which I believe is non-structural) is 4" thick. Their structural panels are the nominal 4 1/2" or 6 1/2" thick.

If you are doing drywall return on your windows and doors, then there is no reason to worry on the windows. But if you want your windows trimmed, then there will likely be added cost.

A standard wall is 4 1/2" thick with exterior sheathing. Standard jambs are 4 9/16" so that the window jamb (presumably wood) is flush or slightly proud of the drywall. So in a 4 1/2" SIP you end up with a 5" wall once drywall is applied. This means you need a custom made 1/2" jamb extensions for every window and door. My windows came from Marvin and they offered no such custom jamb. My builder has resorted to making them, though I argue it should not be difficult if you used 1/2" x 1/4" thick pine or oak strips.

Also, exterior door jambs and thresholds will need to be modified.

I did not use Thermocore SIPs, but looking back that is an attractive feature they offer for timberframe applications.

Andersen windows offer a 7 1/16 factory made jamb which I will be using to trim my SIP house with.  You can get them prepainted white, or raw pine and stain as you like.  Before you price out the jamb extension cost, check if your window manufacturer offers a wider factory jamb.

Best of luck,
Ben Miller

Larry,

Thermocore's 4" panel is structural for a single story house up to 10' tall. If it's taller or more storys, they will havr to be 4 1/2" thick. And you probably will have to have the 1/2" extensions. I suppose you could return the rock, but that would be tedious to me. I usually don't attach the 1/2" strip flush with the factory jamb though. I give the jamb an 1/8" reveal. To me, it adds a little depth and looks better than flush.

We use the 4" panels on our frames, they work out quite well.

I can't think of any other extra costs.

Good Luck,

Thank you all for your replies.

I was trying to see why the extensions would be a big deal, and it doesn't look like they are.

Very respectfully,
Larry

Larry,

Ask your trim carpenter if he thinks the extensions are a big deal.  He's the one that will have to install them.  Also, they add one more reveal line, which may not be an issue.

Don't shy away from SIPs because of the jam extensions, I just came back from my place after finishing up before sheetrock goes up later this week.  It's blowing close to 40 mph and the temp is at 0 degrees F and dropping.  Inside my place it's 72 in the basement, 65 on the main floor and upstairs, and it's 55 in the attic.  All done with radiant pipes in my basement slab and stapled up to my subfloor (though nothings stapled up to the attic floor), powered by an electric boiler rated at 34,000 btu.  Don't skimp on insulation if you want to heat cheap.

My two cents worth,
Ben

Ben,

Thanks for your reply.  I wish that I was at your point:  I live in a 1984 house that was quality when built but exhibits most all of the issues that make me want to build my next house with SIPs.  Unfortunately, I'm still at the thinking stage rather than the contracting stage. 

I guessed that extensions would not be a significant cost, but I was trying to see if there was any contrary experience.  I was even more interested to see if there were any submarines that I'd not considered.

Very respectfully,
Larry

Larry,

When I did my SIP house, I just told the window people what I wanted for a finished jam width, and they said no problem, and they fit perfectly. No messing around with extensions. Oh, they were Jeld-Wen windows.

Steve

GrandCountySIPs.com

Steve,

It's the obvious solutions that always escape me.
 
Thanks!
Larry