Proper install

[rsmitty115]

My contractor has started the process of installing my new full replacement restoration casement windows in my house today. I had asked for a waterproof membrane to be installed on the bottom and up a few inches on each side as an added safety measure against water. Unfortunately I wasn't home when they started so I didn't catch the fact that it wasn't put in until quite a few windows were already put in. The standard install from the contract is to use close cell foam around all edges inside and out, without the use of a membrane. They are willing to remove what they have installed in order to put the membrane since that is what we discussed but have assured me the foam will seal the opening from wind and water. Is foam enough or is a membrane suggested?

[masterext]

To be honest with you, i dont see the need for a " waterproof membrane" on the sill during a replacement, there is no need for it unless its a new construction opening which yours clearly isnt.
However, we actually flash the sill with aluminum and "L" it outward during a replacement but thats me.
Unless using a membrane is stated in the contract and you paid for both the extra material and extra labor, i dont see the need for removing the windows.
Foam is a great air barrier plus its impervious to water.

[TheWindowNerd]

I would not do my own but I would do it that way for you since you asked.
We also use closed cell foam and make sure our caps are well sealed and water lapped.

[Windows on Washington]

+2 to the previous comments.

[HomeSealed]

Agree with the other Pros. It sounds like it is a full tear out, so you are on the right track as to the application. That said, it is not necessarily a standard offering. It DOES provide more protection, and is a "best practice", however it is not a necessary item for a leak free and proper install. It would really come down to what is spec'd in your contract.

For reference, on pocket replacements it is really unheard of and adds little benefit.

[rsmitty115]

Thanks for all the quick responses. I appreciate the help. It is not the normal practice for the contractor to use it but something that I had asked for. I have decided that it is probably not worth the risk of having all the windows removed and reinstalled with the membrane. I will take the issue up with the owner when he returns on Monday. Besides this issue it appears that the windows have been installed with a lot of care. so far happy with my selection.

[HomeSealed]

Definitely worth a conversation with him if it was something that was discussed up front. Beyonf that, it sounds like things are going well.

[toddinmn]

I would say window foam itself is water proof but the seal is not. It would be better to say it sheds water or is water resistant.
Not sure why one would not use some type of membrane or pan at the will and preferably tapered.