Conservatory rot repair

[sjsjsj]

I am replacing my hardwood sills on my conservatory. I have ordered my new sills in hardwood and will mitre them myself. Do I use a biscuit joiner on the mitres to give them extra strength to stop them opening up as I have only glued mitre joints in the past and they have opened up.

I am also replacing the corner uprights and window uprights. I think they are called mullions. They are 100 x 100 mm and I am replacing them with soft wood joinery grade. The original uprights were mt'd into the old sills. As the roof of my conservatory is still on I have limited space to work with a joint. Is it essential I use a mortice & tenon joint to join the uprights to the sill. I can acrow the roof up approx 2cm before it causes problems. With the old sill and mortar out the way I can make my mt joint and glue the uprights into the top timbers which hold the roof on. I am then left with the problem of joining the bottom with no space. Once the new sill is in position on its new bed of mortar, I only have the 2cm space. If I cut a section out of the sill 100 x 100 mm and approx 2cm deep, glue the joint and let the building down so the upright sits into the machined hole - would this be sufficiently strong and is this the right way to get out of this problem? Or is there an alternative joint or metal bracket on the market? Any help gratefully appreciated.

 

[ladylola]

Firstly the mitre , biscuits aren't absolutely necessary but won't hurt being fitted it gives a larger glueing area an may also help if there's any movement.
Second, the joints. In this situation I would , and have many times in the past, use loose or slip tenons. Cut the cill plate as normal with the mortise holes and fit . The upright members you are replacing need to be cut to the correct size but without the tenons.Now on the ends you will need to cut another open mortise or bridle joint (depending on your terminology). It can in some cases be only part way through. This mortise is cut in the same plane as the mortise in the cill and should be marked and cut to be directly above the mortise. The same process is repeated at the head of the frame.
Now cut a seperate tenon that will fit the depth of the mortise in the cill and upright, e.g. if the cill is 2" thick the tenon will need to be 2" plus say 6" into the upright so a total of 8". Again repeat at the head.
Now put the tenons in place( and glue if you wish) and fit the upright by inserting in to the side of it's final position and tapping it over the loose tenons. Just taking the weight off with your acrow will make this procedure easier. Then it's a case of doweling or screwing through the upright to firmly secure the tenons to the uprights.
If you are replacing the corner post there is a slight variation because you can't fit two tenons at once. Fit as per the other uprights but in this case a larger mortise in the adjoining cill will enable the tenon to be slid into place.
Hope this is all clear.