Fitting uPVC Doors and allowing for expansion

24 Oct 2010
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United Kingdom
While uPVC windows are installed with packers and a gap on all sides of the frame (which is finally filled with foam) to allow for expansion what is it best to do with uPVC doors? For the bottom frame (and/or sill) do you

a) make level with packers and leave an expansion gap (just like widows).
b) level the sill with a bed of mortar - supporting it fully (in case trodden on) but leaving no room for expansion.

While windows are hung - have weight supported by the side fixings - does the weight of door frame rest on the threshold? Also does the bottom frame/sill need to be fixed down into the floor to prevent lateral movement especially for wide openings.

Hoping someone that fits lots of doors can advise on what to do for a long lasting well fitting door.
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UPVc doors and frames are stress integral, for want of a better explanation.
The frame is welded all round i.e. with a bottom rail section, and reinforced at all four corners, either by the weld triangulation or some with internal metal brackets. For what it's worth PVC can be counted inert as far as contraction/expansion is concerned in the slap (aperture) The packers should only be at the fixing screws (if used) through the frame, to prevent any distortion, and the void filled with expanding foam, as you have described.
The cill (fitted to the bottom bar) is normally on a mastic bed, but if the clearance is greater, on a mortar bed is fine. This will shrink away from the cill and for that reason should have the weatherseal mastic applied along the meeting joint to effect a seal.
Weight is distributed partially to the cill, but mostly it is taken up via the fixings through the side rails, unless fixing lugs are used to fix, in which case all almost all of the weight is distributed to the cill (making the mortar bed is a good idea)

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