We built a timberframe last winter with a window package from Loewen that included awning, casement, and doublehung units. The first two styles are metal clad on all 4 sides and have a generous perforated steel flange on all four sides for screwing the unit to the building. We have had no problems with these units. The double hungs have the perforated steel flange on the top and sides. The sill, however is fiberglass, and has a small, thin, unperforated fiberglass flange molded to its underside. We shimmed the units up 3/8ths “, and used low expansion foam around the perimeter, as per instructions. The fiberglass flange overlaps the rough opening by 3/16ths to a quarter of an inch after shimming….too skimpy for any screw or nail fasteners.We did the install in January, and all was well until the arrival of warm weather in the Spring. every single double hung sill developed a upward bow in the center…typically 3/8th” belly in the center of a 36″ sill. Has anyone else seen this problem with this model and brand of window? I am trying to get a sense of how prevalent this problem may be, and what the options are to correct it. I have been in touch with the manufacturer, but would like to get some second opinions from this forum as a reality check. Thanks, and Slainte’, Murph
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We have that problem all the time here in Derby City.... with our brick veneers..... they never leave enough room for the settling to the brick sills.... I talk till I am blue in the face.... but, the builder knows it all....
Did you trap the bottom of the frame with shims? I would think that doing so might not allow expansion of the fibreglas sill. Or, perhaps any well fastened exterior casing is not allowing expansion at the sill area?
Quite a while back-'80's, Andersen had problems with their wood sills on their dbl hungs. Not sure the cause but the result was a big bow up of the sill. In many cases they replaced the whole unit on warranty.
A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
no shims at sill ends....fastners in provided flange holes . 1/8th " gap @ exterior casing. These sills bowed to the extent that the factory paint crackles and flaked off.I wonder what the thermal expansion cooeficient is for fiberglass ?
I have no idea the properties of fibreglas, but what has Loewen said about this problem?A great place for Information, Comraderie, and a sucker punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/