Water penetration above conservatory glazing.

[RonnyRaygun]

I am soon to construct a new conservatory. It will be a lean-to type and on the one side will attach to an existing extension.
The pitch of the glazing will be 13 degrees. However, the existing extension roof is flat for the first 2 metres and then slopes at 45 degrees to the eaves.
This will leave a significant area of exposed blockwork where rainwater will hit and potentially soak through and cause a damp problem below.
I know cavity trays can be used but I can't see how in this instance when the glazing is sloping.
Would taking flashing up to roof level and covering all the exposed blockwork be an option?
Alternatively, could a proprietary waterproofing coating or render be used?

Thanks,

Craig.

 

[RonnyRaygun]

Anyone??

 

[freddiemercurystwin]

Photo?

 

[RonnyRaygun]

Sorry for my ignorance, how do I upload files?

I haven't got any photos but I do have a drawing which will probably help.

Cheers,

Craig.

 

[freddiemercurystwin]

A drawing will be better than nothing I suppose. You will still need to photograph it or scan it and then upload it though. Can you not borrow a digital camera from someone or use a mobile phone?

//www.diynot.com/forums/viewtopic.php?t=129539

 

[RonnyRaygun]

Untitled

• RonnyRaygun
• 11 May 2010
• 1

OK, drawing uploaded. Couple of bits of free software did the conversion from .dwg to .pdf to .jpeg. Hopefully it's embedded correctly in the message here...

Should point out that the wall of the extension is blockwork and not brick as shown.

 

[freddiemercurystwin]

Well the roofers will proably be along later but heres my two pennys worth, theoretically a stepped cavity tray should be retro-installed in the cavity. These can be stepped as you go up the slope of the roof. However obviously its easier said than done and would involve removing chunks of masonry (you fit them in sections not in one go) so bit of a pain.

Is the blockwork rendered or just exposed blockwork?

In any case I think you should fit a lead flashing cut into the blockwork under a render stop following the pitch of the glazing. If you do eventually get damp penetrating out through the wall at lower level you can decide to fit a cavity tray later.

 

[RonnyRaygun]

Thanks for your thoughts Fred's twin.

Retrofitting stepped cavity trays does sound like a pain and something I'd rather avoid if possible!

The wall is currently bare but is due to be rendered prior to the fitting of the glazing (this'll give me smooth walls to plaster in the conservatory).

So roofers, any more pearls of wisdom or is the option outlined by Fred the one I should go for?

 

[datarebal]

If the walls not rendered already you could cut a chase from top to bottom and fit a flashing into this. (observe the 1.5 metre rule). when securely fitted point in joint with lead mate or similar. Then before it's rendered use a stop or bell bead to partially cover the joint and if possible seal the bead to the lead as well. Then Render.

Or knock down block work and fit trays.