To cut into side of house or not? ( lead flashing)

2012paddy2012

Just an enquiry please.
I’m getting a couple of quotes for a lean too out from the back of the house and was going to put paving slabs under it .

A couple of the quotes were basically similar re the construct of same .re necessity for gutter or not.. how to get rid of water run off , when raining ... etc ...

One chap said it would be important to cut in to the brickwork on back of house and place lead flashing
There coming out on to the timber ...in order to ensure that water doesn’t get into the rear house wall .

( I did have a full proper extension before and that was done )

Another said ah no need we can just put mastic along that point on the wall and that will seal the timber appropriately ...

I also had a Lean too before and it was done that way and I didn’t have any issues ...

I am not sure which is the best way to go ... appreciate any advice. It’s perplex or polycarbonate sheets just fitted into a timber posts in the garden , a basic lean too ...
Thanks
Paddy

GreeBo

If it was me I would flash it with lead

listermint

Lead, always the lead. You do not want water ingress back into brickwork in your house - No Bueno. If your going to the bother of paying good money for this make sure its dont right and lasts.

2012paddy2012

listermint wrote: »

Lead, always the lead. You do not want water ingress back into brickwork in your house - No Bueno. If your going to the bother of paying good money for this make sure its dont right and lasts.

Really appreciate that , I had thought that was a more permanent better way to go . I will do that.

Regards and thanks
Paddy

jack of all

100% lead, as others have already said. My brother got a lean-to structure put onto the side of his house last year and it was just sealed with caulk. He was advised by the installers that it would need a lead flashing but they wouldn't do it, they just tempoarily sealed it with roofing caulk, fair enough. With poor weather and life getting in the way it was left for over six months and no water got in. We eventually made a date to do the work and a few days before the appointed Saturday there was a week of heavy rain and it started to get into the new structure! The two of us fitted a new lead cover flashing in a day and no problems since. It's not an expensive job to do, so no point skimping.

Calahonda52

I would not go the lead route for such a roof, no need.
I have used
Foil Tack Band Butyl tape from a crowd in Dublin.
They will cut it whatever width you want.
I buy it in 150mm wide rolls, 5 meters long.
They are open, if you pre-order and prepay, you can collect from the door

It's flexible and tacky and does not set hard.
In fact I have used it to repair lead flashing on a glass roofed conservatory when rain drove up under the lead

listermint

Calahonda52 wrote: »

I would not go the lead route for such a roof, no need.
I have used
Foil Tack Band Butyl tape from a crowd in Dublin.
They will cut it whatever width you want.
I buy it in 150mm wide rolls, 5 meters long.
They are open, if you pre-order and prepay, you can collect from the door

It's flexible and tacky and does not set hard.
In fact I have used it to repair lead flashing on a glass roofed conservatory when rain drove up under the lead

The application you suggested there had lead already cut into the block work. you patched over a different join to the glass roof.

Tapes are grand (i have various ones in the house)

They are not a good solution for the transition from brick to roof though. Theres a reason you dont see them used by professionals for this application.

GreeBo

If you think about it, neither brick nor render is water-proof so even if your mastic/silicone is waterproof, water will get behind it.

listermint

GreeBo wrote: »

If you think about it, neither brick nor render is water-proof so even if your mastic/silicone is waterproof, water will get behind it.

Its not about the waterproofness of the substance its about pushing the water at speed away from the envelope of the building.

Dr Turk Turkelton

listermint wrote: »

Lead, always the lead. You do not want water ingress back into brickwork in your house - No Bueno. If your going to the bother of paying good money for this make sure its dont right and lasts.

This.
And also go with the guy that suggested the lead first and avoid the cowboy that said to use silicone.

GreeBo

listermint wrote: »

Its not about the waterproofness of the substance its about pushing the water at speed away from the envelope of the building.

Yep, that was my point.
If you glue something to the side of your house you are effectively diverting water into your house rather than down the side of it; hence you are relying on the waterproofness of your substance...which typically isn't waterproof at all.

Lead overcomes this be being behind the render and diverts water back out onto the flashing.

TheBoyConor

Cutting in the lead would be the way to go definitely if the space underneath the proposed lean to was an indoor area. It is not. It is just a storage shelter for firewood and bikes and so on.

I think there is also a risk with cutting in the lead flashing.
The worry I would have with cutting in the lead is that can you be sure that the contractor is going to adequately infill and point the saw cut so that the edge of the brick still has full support? Or are they just going to do an "on the tools" or "tradie mayhem" type job and point the surface or the bits you can see and "she'll be 'right, mate" for the rest of it? If that is the way it will be done then there is even more rainwater going to penetrate the wall through the cut and that could lead to all sorts of issues with the brickwork cracking and deteriorating over time. My experience with contractors is that any shortcut that can be taken will be taken if it can be gotten away with.

For that reason, I would say that it is a safer bet to screw and mastic the flashing onto the wall.

At the end of the day, worst case scenario and the mastic eventually fails, there isn't going to be any more water on the wall than would be if there was no lean to. It is still an external wall exposed to the outside.

Try your best, silicone the rest.

2012paddy2012

TheBoyConor wrote: »

Cutting in the lead would be the way to go definitely if the space underneath the proposed lean to was an indoor area. It is not. It is just a storage shelter for firewood and bikes and so on.

I think there is also a risk with cutting in the lead flashing.
The worry I would have with cutting in the lead is that can you be sure that the contractor is going to adequately infill and point the saw cut so that the edge of the brick still has full support? Or are they just going to do an "on the tools" or "tradie mayhem" type job and point the surface or the bits you can see and "she'll be 'right, mate" for the rest of it? If that is the way it will be done then there is even more rainwater going to penetrate the wall through the cut and that could lead to all sorts of issues with the brickwork cracking and deteriorating over time. My experience with contractors is that any shortcut that can be taken will be taken if it can be gotten away with.

For that reason, I would say that it is a safer bet to screw and mastic the flashing onto the wall.

At the end of the day, worst case scenario and the mastic eventually fails, there isn't going to be any more water on the wall than would be if there was no lean to. It is still an external wall exposed to the outside.

Try your best, silicone the rest.

Ok thanks not I’m not so sure I’m back where I started .. but thanks all

2012paddy2012

Dr Turk Turkelton wrote: »

This.
And also go with the guy that suggested the lead first and avoid the cowboy that said to use silicone.

Thank you