Expert: Richard Taylor, AIA - 4/20/2009

Question
Richard,

I recently decided to have replacement windows installed in my home. After placing an order for the windows, I decided to change my siding. The siding person suggested that we change the order from replacement windows to new construction windows since they have a nailiing flange, but the window company said that it was too late for this change. The replacement windows were installed first and now the siding is being replaced.  The siding person tells us that the windows were installed too far in and he believes that the windows will leak. I questioned the window installer. His reply was that he had to go that far in to get the stud.

My question is, how can I determine if these windows were installed properly and I will not have problems with leaking and drafts down the road?  The siding installer is insisting that the windows were not done right and the window installer insists that they were. Where can I go for help?

Answer
Good morning Frank, thanks for your question.

I've never heard of installing windows "too far in".  Replacement windows are designed for the thickness of the wall; they only fit in one place.  The inside of the frame face should be roughly flush with the drywall; the outside should extend beyond the sheathing, either with pre-installed trim overlapping the sheathing or with the trim flush with the window opening.

Ideally, windows with nailing flanges are installed first, then siding is installed over the flanges.  But the flanges aren't for shedding water, they're for attaching the window to the face of the sheathing from the outside.  Since many replacement windows are installed from the inside, this isn't a critical detail...it's a convenience.

Either way, it's the window company's responsibility to properly install and trim their product - whether the siding is existing or new.  Your two installers need to get on the same page and figure out how they're going to trim the exterior before they go any further.

Before you start installing the new siding the windows should be completely installed - including the exterior trim.  Then the  siding installer's work is completely on the face of the wall.  All he'll need to do is counterflash the top of the trim, install the siding, and caulk the joint.  The window and trim should be all one contiguous installation; the siding comes later.

It sounds to me like the window installer hasn't finished his job yet...ask him about the trim detail.

If you can't get agreement between these guys, contact the National Association of the Remodeling Industry (NARI) - both are likely members.  They have dispute resolution services that can determine who's right.

Hope this helps!

Richard Taylor, AIA
www.rtastudio.com
www.rtaplans.com