Parapet Repairs : Long-term vs Short-term

[rideforever]

I have had leaking parapet wall > the interior walls were wet ... and we just had it sealed over.

What is the long-term solution ? The seal is only going to last a few years isn't it ... is it possible to re-render the entire wall or ... does it need to be totally flashed over with lead ?

Any help would be great.

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• rideforever
• 17 Feb 2014
• 2

 

[palaceray]

The best idea would be to have the rendering hacked off and to re render the wall with water proofer in the mix. To complete the job it would be best to cap the top of the wall in lead if your budget allows.

 

[ree]

Pics of the whole parapet would help.

What do you mean by "sealed over"?

Is it definitely leaking through the parapet only, or maybe through the flat roof as well?

Any remedial repairs must take into account the flashing arrangements at the base of the parapet.

Given that your neighbours are involved in any repairs then maybe the whole parapet brickwork be exposed before any determination on a final cover is agreed.

On the far side parapet of your neighbour's roof they appear to have coping stones, or similar, installed.

 

[rideforever]

Sealed over : well a roofer came and hacked out some cracks and filled them, and then put this "aqua seal" grey stuff over - although it's been only 6 months and the aqua seal is very thin and wearing away.

Sorry about the photo : the seal goes up to the apex and then stops, the render being as it was on the other side. It's not a flat roof but a dormer with lead that you can see ... on the other side the neighbours just have tiles and a velux there (I have indicated the velux as a possible cause). Leading all looks good, although I have just mastic'ed 2 vertical seams that I wasn't sure about.


Although the damp is much improved with the work that was done, some is still entering ... from an unknown location ... and seems to be getting a little worse now. My guess is that the render is the problem; the aquaseal would have fixed it 100% if it hadn't been bodged; the aquaseal is now wearing off so its getting worse again.

I have told the neighbours the best bet is (a) to totally go over this grey aqua seal again ... and if all the damp stops then at least we know where the problems is and that is a good start. Then (b) do a permanent repair.

Long-term solutions I don't know about. Everyone here in Brighton seems to be just painting this aquaseal over their parapets ... but frankly I want to do a good long-term job and not have to go up on the roof ever year and worry about it.

The question I ask is - the original render probably lasted 50 years - so what's with all this aquaseal business ?

It was £400 to get the work that was done, and it has lasted maybe 12 months - which is ridiculous.

How much is re-rendering really going to cost ?

Anyway I have spoken to 5 roofers ... all of them want to fill the cracks ... and apply aqua seal !!!

 

[ree]

Pics of both sides of the parapet itself please, up to and over the ridge (apex), thats if your property goes to the other side.

Pics of the dormer leaded area as well will help. Stay away from silicone/mastic.

Where is the damp presenting inside the building?

Why do you suspect the Velux?

As you would expect from a professional in the building trades, i suggest that you bite the bullet, and do a best possible (and most expensive in the short term) job.

Its possible that when the render is removed it will expose brickwork that must be replaced and re-built, but who knows?

 

[rideforever]

Here are all the photos. As you can see about 3m of the wall was aquasealed and cracks filled.

The interior is just visible through the window. It is damp for about 1.5m from the window on the interior ... 50cm beneath the roof line.

There is no damp / damage on the interior on the ceiling nor around the window frame ... i.e. it looks to be coming from the parapet render or possibly the flashings ... but the flashings look good and I masticked 2 vertical seams just in case with no improvement.

The neighbours have damp their side opposite our damp. Theirs is much worse.

Anyway, any information on how to do a repair that would last as long as the original house build (50years+) would be grateful received. Cheers

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• rideforever
• 17 Feb 2014
• 2

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• rideforever
• 19 Feb 2014
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• rideforever
• 19 Feb 2014
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• rideforever
• 19 Feb 2014
• 1

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• rideforever
• 19 Feb 2014
• 1

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• rideforever
• 19 Feb 2014
• 1

 

[palaceray]

As in my first reply: hack of the render and have 2 coats of rendering done with waterproofer in the mix.

Fix 19mm ply on the top of the wall and cover with a lead capping.

I would guess the cost would be about 3k plus any scaffold that is needed. It may seem expensive but it is the right way to do the job.

We did a roof in Brighton last autumn and some of the work done on roofs in the mews of the sea font is truly awfull

 

[rideforever]

3k !!!!

What about re-flashing the whole thing instead ?

 

[Nige F]

Sealed over : - so what's with all this aquaseal business ?

It was £400 to get the work that was done, and it has lasted maybe 12 months - which is ridiculous.

How much is re-rendering really going to cost ?

Anyway I have spoken to 5 roofers ... all of them want to fill the cracks ... and apply aqua seal !!!

. you`d get an idea on the plasterers forum of the cost of render - then there is the scaffold etc. You have found what a LOT of Sussex " roofers " are like . I know a couple of good builders who would work in Brighton - get back to us here when you are going to get it done

 

[ree]

rideforever,

Thank you for the photos.
1. The top surface of the parapet, just above the soil pipe and also a bit further up, has been "repaired".

2. There's also a repair line on the parapet side running just above what seems to be a one piece cover "flashing".

3. Render on left side of the parapet appears to go down to the flashed tile? Is there any cover flashing?

4. Flashing at the bottom of the Velux has been pieced in.

5. The lead flats are very flat (there are no "vertical seams" in the lead). But it looks to be first class leadwork.

6. A tile has dropped at the second bay.

7. The window frame has been badly installed: non-recessed and too low. Something not right at the vertical LH side of the frame?

8. The lead flashing at the corner above allows water to run down the frame and wall.

9. The white painted black plastic soilpipe seems to be indenting into the parapet edge. (never paint plastic).

10. The interior damage runs down to the skirting - maybe behind it, perhaps even into the floor. The plaster will have to be renewed at some time.

11. Someone should water test the roof and parapet. Starting at the gutter and working up to the ridge. Do the same to the parapet. Its a slow methodical process with a hose pipe.

I suspect the parapet but the whole roof must be tested and examined, esp. where flashing looks odd or repairs have been attempted.

 

[Alastairreid]

The tiles either side of the 2nd bay have been pushed up to accommodate the ridge roll! no tile slippage.

Counter flashings below velux windows is acceptable! thats next door anyway.

Do as palaceray said!! and get a few quotes.

 

[rideforever]

I have done ranging from £600 to £1200 ... but it's all the same, fill the cracks and aqua seal + a bit of flashing work maybe

 

[Alastairreid]

Do you have any problems on the front elevation?

Anyway, get a builder to quote for removing back to brick existing render, renew lead aprons to dormer roof if required, run dpc along top of parapet and install coping stones.
2 coat render with waterproofer to complete.

Oh and bellcast beads along the lead detailing.