Jump to content

Advice on sealing roof window


H F

Recommended Posts

The previous owners built a conservatory with two roof windows. The sealing is a complete dog’s dinner. They’ve used flashing and with all the rain we’re worried about water ingress leading to leaks.

 

We are wondering how to best seal these windows once the lead has been removed. It’s likely to be a spring/summer job but would like to plan for it now.

 

suggestions and advice, as always, is welcome.

BBD52440-AF20-41BD-A7C2-8F50E7BFC670.jpeg

AAC3ED5C-F63F-459B-999C-1B0CC7299575.jpeg

3569590D-98B0-4885-AA59-BA1482214594.jpeg

Link to comment
Share on other sites

I would not give that the satisfaction of being described as a "roof window"  It look like some DIY bodge job.

 

What's the roof material?  it looks like box profile sheets cut into strips?

 

The lead flashing above the window needs to be longer and tuck under the roof cladding strip above it, not end just below it with half a tube of some sealant hoping to seal it.

 

And the same with the side flashings, they need to be longer so they tuck under the roof sheet above.

  • Thanks 1
Link to comment
Share on other sites

It’s a horror story isn’t it? Glad you agree,

 

The roof surface is called Plastisol - it’s a sheer metal that can be used for roofs.

 

Would you recommend replacing the lead with something else? Not sure lead flashing was the right option here.

Link to comment
Share on other sites

"Plastisol" is actually a plastic pvc coating applied to sheet roofing to protect it further over a normal galvanised coating from water ingress. It can also be used to give colour. 

 

See:

https://www.cladco.co.uk/choice-of-coatings

 

I have a sunlounge roof done in plastisol coated box section corrugated with a roof angle of about 6 degrees. 6 years on, no problems. No windows in it, however.

 

To me there do not look to be enough fixings in the pic - though light by only perhaps a third, which may be OK.

 

What to do?

 

If you are not currrently getting leaks I would leave it until probably May (ie when the dry season starts), and have thought about possible solutions before then. If you are getting leaks I would jury-rig until the weather is less waterfall-like.

 

Corrugated is good at keeping water from tracking sideways, and I think your issues will be water up the roof coming in the top edge,  and water on the window running under the seal. 


As to a permanent solution? Perhaps see if there is a kit from somewhere the right size which would fit, or make the window a bit bigger and make it proud of the roof service. I would try and avoid wholesale roof replacement, but otoh corrugate dis tricky to cut.

 

Ferdinand

 

Edited by Ferdinand
Link to comment
Share on other sites

  • 1 month later...

We tried to see this off until the summer. Not that lucky. We’ve sprung a leak - I think the black stuff is mastic but it seems to have degraded. Does it degrade over time?

 

Any solutions?

 

During a dry spell, should we rip this stuff out, clean it, and replace it? If yes, what would be recommended? Mastic, silicone?

 

Really fed up with other people’s shitty workmanship. 

AD96F8D6-BA0A-4AFC-BB61-8D3C0545E17E.jpeg

A4CF4F66-0540-4BDA-B1CD-031DB8599A2D.jpeg

AC65228A-E150-4B8F-B15D-AD249FFB958E.jpeg

Link to comment
Share on other sites

Before you can address the problem, you need to know where the water is getting in.

 

Initially I thought it was the poor detail at the top where the top flashing is not correctly tucked under the sheet above.

 

Are you now thinking it is getting in at the edge of the glass and there has been a previous attempt to re seal it there?

Link to comment
Share on other sites

How much money do you want to chuck at it..... by the time you strip out the lead and find a bunch of rotten wood to strip out..... and then realise that as it’s just a double glazed unit bodged in from the start your going to have to Heath Robinson the thing again as you can’t actually buy a flashing kit for it........  how about a nice new Velux with a propper flashing kit and you end up with a window that will open when you want and will last a very long time.  Go crazy and redo that lovely .... fake tile tin while your at it  and put in a few extra windows........   just an option to consider........l 

Link to comment
Share on other sites

I don't know if this will be much help, but I have just ordered my rooflights for my forthcoming build and here are the cross-sections and installation instructions for them. I might give you some insight and thoughts about your own rooflight problems: https://roof-maker.co.uk/rooflights/flat-rooflights/fixed-flat-rooflights/

Edited by Dreadnaught
Link to comment
Share on other sites

36 minutes ago, ProDave said:

Before you can address the problem, you need to know where the water is getting in.

 

Initially I thought it was the poor detail at the top where the top flashing is not correctly tucked under the sheet above.

 

Are you now thinking it is getting in at the edge of the glass and there has been a previous attempt to re seal it there?

It’s getting through the top. I just took the photo from the bottom to show the mastic.

 

Maybe it needs to be tucked in better.

Edited by Home Farm
Link to comment
Share on other sites

21 minutes ago, Cpd said:

How much money do you want to chuck at it..... by the time you strip out the lead and find a bunch of rotten wood to strip out..... and then realise that as it’s just a double glazed unit bodged in from the start your going to have to Heath Robinson the thing again as you can’t actually buy a flashing kit for it........  how about a nice new Velux with a propper flashing kit and you end up with a window that will open when you want and will last a very long time.  Go crazy and redo that lovely .... fake tile tin while your at it  and put in a few extra windows........   just an option to consider........l 


We have considered that. The other massive issue is that the existing windows are a custom, stupid size... so we can’t like for like change it. 
 

We might have to do that in the summer though... just need a fix for the next few months.

Link to comment
Share on other sites

22 minutes ago, Dreadnaught said:

I don't know if this will be much help, but I have just ordered my rooflights for my forthcoming build and here are the cross-sections and installation instructions for them. I might give you some insight and thoughts about your own rooflight problems: https://roof-maker.co.uk/rooflights/flat-rooflights/fixed-flat-rooflights/


Thanks for that. It might cast some insights.

Link to comment
Share on other sites

If we were to remove the lead, what else could be used to keep the water out going forward? 
 

I guess my question is, how do professional gutters fit custom windows that don’t come with kits.

 

 

Link to comment
Share on other sites

On 20/12/2019 at 12:40, Home Farm said:

BBD52440-AF20-41BD-A7C2-8F50E7BFC670.jpeg

AAC3ED5C-F63F-459B-999C-1B0CC7299575.jpeg

3569590D-98B0-4885-AA59-BA1482214594.jpeg

This is the problem imho.  That lead at the top should be much longer and tuck UNDER the roof sheet above the window.  At the moment at best it buts up to the joint between the roof sheets and has a tube of sealant trying to stop water getting under the lead.

 

So start with replacing that with a larger strip of leas that really tucks under the roof sheet above the window.

 

Because the rest of the window is also a bit dubious, I would try and form a bit of an upstand in the leadwork so instead of allowing water down onto the glass, it encouraged it to run off the sides above the window and down the roofing sheets

 

While you are at it, the lad down the sides should be wider so they at least lap down into the first valley of the roofing sheets. At the moment water on that flat section can blow under the lead.

  • Thanks 1
Link to comment
Share on other sites

There's also a potential problem with using lead above a window, as the glass will end up being stained by the lead salts that wash out over time.  As a general rule it's best to try and arrange things so that there isn't much possibility of water running off lead flashing on to glass.

  • Thanks 1
Link to comment
Share on other sites

5 minutes ago, Roundtuit said:

If you want a short-term fix with a view to doing a proper job later, I'd Flashband it to death. A bit of heat from a hot air paint stripping gun and it sticks to most things!


‘yes I would try to avoid using any lead as it’s gets very expensive very quickly, I like the idea of either doing it well or spending as little as possible and not worry what it looks like as long as it’s waterproof. If flashband or another product will stick to the roof and glass then possibly strip the lead off, clean it all up and do a good temporary fix with some flash band or equivalent. 

  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...