Window sill slope on building - Contractor Talk - Professional Construction and Remodeling Forum

Flatrooferstl · 09-06-2009, 12:33 PM

Im waterproofing a building for a customer and have found much interior damage due to the exterior window sills being open at meeting points of brick sill and window itself. how long would caulking lasts and would it be better to apply new slope of concrete mound towards outer building to guide water.

SealantEngineer · 09-14-2009, 03:15 PM

depends on what you use... Ureatheane sealants will you 2-10 years depending on exposure. Latex will get you 6 months to 2 years, painting it will help in both uretheanes and Latex. A "Good" Nutural cure silicone will last 10-50 years. Dollar for dollar Dow Corning contractors weather proofing sealant will be the best. Performance wise i would say Dow Corning 790... Check on the SWRI web site you will see both products highly rated.

Also, the sills should be sloped away from the building atleast 5 degrees... If someone put sills installed sloping towards a building they should exiled from contruction.

nEighter · 09-14-2009, 04:42 PM

The code states elastomeric.. but eurathane will surely be a good alternative. Do it right, don't go cheap and all will be good. Tell them the life expectancy and let them know they will have to check the windows every 3 months or so to make sure the caulking is holding up.

WNYcarpenter · 09-14-2009, 06:08 PM

redoing the sill would be best...I wouldn't trust caulk too long. Can you rivot a metal "L" bend to the window the caulk?

Any pics?