How to make conservatory roof water-tight?

TuppenceHapenny

I'm trying to stop water getting in through the roof of a 20-30 year old timber-framed conservatory. It's getting in where the plastic (polycarbonate?) roof sheets meet the wooden bars of the frame (i.e. the glazing bars?). The plastic sheets expand and contract so much in summer that normal silicone sealant doesn't work - it stays bonded to the plastic sheet but is torn away from the timber frame bars leaving a gap where water gets in. Can anyone advise what to use? Thanks.

Ruski

Could you retro fit these?

https://www.ebay.co.uk/itm/50mm-Screw-Down-Glazing-Bar-Sunwood-Conservatory-LeanTo-Roof-Polycarbonate-Glass/371778537588?hash=item568fba4874:m:m6-xs_IGPRMcNqHYBNWg3vg

Russ

TuppenceHapenny

Ruski wrote: »

Could you retro fit these?

https://www.ebay.co.uk/itm/50mm-Screw-Down-Glazing-Bar-Sunwood-Conservatory-LeanTo-Roof-Polycarbonate-Glass/371778537588?hash=item568fba4874:m:m6-xs_IGPRMcNqHYBNWg3vg

Russ

Thanks for the reply.
Unfortunately these don't look suitable because of the conservatory design. Don't have a digital camera to post a photo, but the glazing bars sit proud of the roof with the plastic roof sheets attached at the bottom of the glazing bars, with a 5mm gap between the bottom of the glazing bars and the roof sheets (where the water gets in). So it strikes me that I need something to go into the 5mm gap between the bottom of the glazing bars and plastic sheets.

Furts

Post some photos of your roof and folks may be able to brain storm some answers for you

TuppenceHapenny

Not my conservatory but roof construction is the same, except my roof is much more gently sloping.

The circled area shows were water tends to get in most - it pools up slightly behind the lip along the edge of the plastic roof sheets and then finds its way in at the gap between the roof sheets and the timber frame bar.

TuppenceHapenny

This is an attempt at a sketch diagram showing the problem.
I could probably get the original seals replaced but would have to get a conservatory firm in to do it and it would presumably cost hundreds, so I'd prefer to avoid that.
I think it should be possible to do something cheaply myself with the right material. I've tried putting normal silicone sealant along the gap between the glazing bar and the roof sheet but it gets torn away from the glazing bar as the roof sheets expand and contract in warm weather. Can anyone suggest what would be the best thing to use instead of silicone sealant in light of the expansion/contraction problem (e.g. specialist sealant or putty, rubber gasket, waterproof tape of some kind, etc)?

Furts

Silicone would work provided the joint is the right ratio of height to depth. It sounds like there is not enough height. I suspect rot and dirt with the timber is also an issue - you do not have a clean, prepared surface. Two long shots - can you reseal each year as part of a maintenance regime? Seems like it is a minor job. The other is you could try Compriband to seal the gap - not sure this is ideal as a bitumen type product adjacent to polycarbonate. You have a think here, but your roof is old so what have you got to loose?

The idea with Compriband is it expands to fill a gap, so your heat and expansion will pull on it, but when cooling occurs it might go back to where it was. You would silicone over this, so really your Compriband is acting like a backer rod.

If the gaps are tight you might just forget the Compriband, put in polyethylene backing rod and point it over with silicone. It is a trial and error thing.

Lorian

Google "rubber glazing gasket" and select images. You can get all sorts of shapes and sizes.

Furts

The seal has been sketched by OP, but I do not know if this is a wrap around detail going on the edge of the polycarbonate, or whether it is inset into the timber. If the latter, the I am guessing rot is an issue and a new seal will not work

booned

• Take the affected timber bars off and look for signs of rot.
• If they are beyond saving, buy some new ones.
• Let the good ones dry out completely
• Buy a good quality epoxy or wood filler and restore the beams if needed.
• Treat the wood with a good quality wood treatment oil.
• Remove any bad seals and any other debris (silicone etc)
• Buy some expanding foam tape to replace any bad seals.

TuppenceHapenny

Thanks for the reply.

Furts wrote: »

I suspect rot and dirt with the timber is also an issue - you do not have a clean, prepared surface. Two long shots - can you reseal each year as part of a maintenance regime? Seems like it is a minor job.

Picture doesn't show my conservatory, just one with the same sort of roof construction as mine. My own roof is cleaner than this so the silicone does stay bonded to the plastic sheet and bonds to the frame bar until roof sheets next expand and contract. In theory I could try squeezing more sealant into the gap that results when the sealant pulls off the glazing bar but there would be times when I would have to do this on a weekly (if not daily) basis so I don't think it would be a practical solution.

Furts wrote: »

The other is you could try Compriband to seal the gap - not sure this is ideal as a bitumen type product adjacent to polycarbonate. You have a think here, but your roof is old so what have you got to loose?

I have seen elsewhere that bitumen based flashings will attack polycarbonate so I would prefer to avoid anything with bitumen if it could damage the roof sheets. They are a bit old but still seem to be intact and undamaged at present.

Furts wrote: »

If the gaps are tight you might just forget the Compriband, put in polyethylene backing rod and point it over with silicone. It is a trial and error thing.

Thanks - I might investigate this further and give it a try.