Perfect weather for a day on the roof - parapet problems

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Happy New Year all,

I was in the loft earlier today, stashing all the pointless junk that my family have bought me over Christmas and got a bit of a shock when I saw the rafter closest to the party wall (Vic terrace) was soaked, as were the first 2 courses of bricks as you moved down the pitch of the roof. After yesterdays terrible weather I was hoping that it was as simple as a tile blown off but no such luck .... after dusting off the ladders and roping in my brother as dead weight (something he's become very good at over Christmas), I climbed up and saw a few problems. I'm by no means a pro but I'll have a go at explaining what I could see and any advice on how best to repair would be great. The attached picture shows my roof with the terracotta tiles and my neighbours with the darker tiles.

http://media.diynot.com/170000_169334_71029_57582872_thumb.jpg

1/ The render on the top of the parapet wall is cracked/blown in some parts.

2/ Some of the mortar where the lead is bedded in between brick courses has crumbled and so the flashing is loose.


I noticed that the neighbours flashing doesn't look stepped like mine and they have a render down to the flashing. Can someone explain if the render covers the top of their flashing or do they have a flashing that isn't bed into the bricks and therefore the render above the flashing acts as lip to stop water ingress where the flashing meets the brick? Hope that makes sense!

Would it also be an idea to set some coping stones or tiles on top of the parapet wall, a lot of my neighbours seem to have these?

Like I say, I'm no pro but I'm fairly handy and don't mind spending a day or two with a hot flask and a packet of digestives sorting it out rather than forking out for a proper pro!
 
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Sorry that picture is tiny.

I think this will work. If not the picture is in my diynot album.

 
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Not a roofer but my parrapet walls [end of terrace 30's property] caused endless leaks until I capped them.
 
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That's what a lot of my neighbours have had done I think. By capping do you mean a coping stone or tile on the parapet, or did they use a felt or lead to cover (cap) the top of the parapet?

Here's a picture of the neighbours with tiles set in mortar on top of the parapet. Half the street have had something similar done. This picture also has the straight (ie not stepped flashing) with render directly above the flashing. I'm interested to know what the difference is between this and my parapet?

 
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Longer term you probably want to keep the render in good shape but unless the wall has deteriorated badly then the flashing is the most likely source of leaks.

There are various guides for flashing detail on the web, for example this one from British Lead shows some detail relevant to yours..

http://www.britishlead.co.uk/downloads/fitting-guides2.pdf

Worth checking that edges are secure and that it's properly chased and sealed into the wall. If you decide to replace it all, clips can make the job of securing the lead a bit easier and quicker..

http://www.britishlead.co.uk/hall-clips.htm
 
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Thanks for this.

Luckily, there is a good roofing supplier around the corner so I will pick some of those clips up. Would you advise using the lead pointing sealant too or stick to mortar?

So here is my plan, if anyone could advise on the specifics or if I'm missing a step that would be very helpful.



1/ Chip out dodgy pointing on loose flashing (any particular depth or just enough to get flashing full in?).

2/ Use the clips to wedge the flashing fully in and use a mortar or lead pointing sealant to fill.



Then I would also like to repoint the bricks on the vertical face of the parapet. If I get up there and realise that the majority could use repointing, would it be more sensible to render the vertical face, or is it better to repoint to retain the depth of the lip from the protrubing brick? If ok to render, would I need a stop bead sitting just above the line of the lead flashing?

From the guide, it looks to me as though the neighbour has soakers fitted on top of their stepped flashing and then the render comes down to the top edge of the soaker, rather than my roof which simply has stepped flashing without soakers. Is this right?

Finally, if I sort out the top face and vertical edges (above the protruding brick) of the parapet, what would be the method? Depending on the amount of loose render I would think to either

1/ chip away loose bits and repair with mortar
2/ chip away all render and re-render using either exterior corner beads or temporary fix wooden batons for guide
3/ repair vertical face and then bed in some coping stones/tiles.

Sound sensible or am I missing something? Also any tools that you think might come in handy please shout. I intend to pick up everything I need today and start as soon as I get a break in the rain.

Many thanks
 
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I would grind out all cement to the flashing and make sure the lead goes at least 25mm into the wall and then point with lead sealant. Lead moves - mortar doesn't.
With regards to tour wall top I would go for your third option but use angle cap tiles at 115 degrees. your roofing supplier can sort these for you.
Lastly, please work safely.

Good luck.
 
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Your plan seems pretty sound, finishing the flashing with lead seal from a caulking gun sounds a good idea, especially at this time of year when low temperature and rain can make curing mortar a problem. Only one I would add to your list is to consider treating the open joints with a waterproof bonding agent after they are raked out and before fitting the flashing and sealer. It would stabilize the surfaces and help the sealer to bond.

It's personal preference whether to repoint and/or render. Where the bricks are in reasonable shape I tend to avoid render - you can see what's happening to a pointed wall but render can conceal future problems and make them worse.

Your roofing supplier can be a good source of advice for the best products, a lot depends on local conditions and they will know what works where you are.

Tiles or other capping on the wall sounds a good idea but I'd leave it until the weather improves if you can. A lot of early failures of mortar are due to poor curing conditions during the first few days so warmer drier weather can give you a more durable result.
 
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Thanks for all the advice.

I had a chat today with the roofing suppliers and armed with their advice and your own, I'm going to get up on the roof again, as soon as the wind and rain give it a rest, and get some measurements and take a more educated look at what my plan of attack will be.

I'll take a few snaps while I'm up there just to get you to cast a final professional eye over it before I crack on, which will be as soon as possible for the flashing and as soon as the weatherman predicts a few days of mild, dry weather for the tiles.

One last question before then; if I render the vertical face, I presume I can use the current brick lip as a 'stop bead' (as I will be using tiles which will replace the need for the lip), but how far down can I go? As I've now learnt that mortar over lead is a bad idea, do I run an exterior stop bead so that it runs just above the stepped flashing and render down to this?

Thanks again
 
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Hi all,

As promised, here are a few of the best snaps of my day trip to my roof.

I made a start today sorting out the flaunching which I realised was probably causing the bulk of a leak in my bathroom. Photos are:

Flaunching gone to pot

Fillet kippered

Parapet rendered ....... useless

Parapet ..... (I'm out of puns)

Flashing exposed

The plan is to redo the flashing with the clips and lead mastic that I've bought from the local roof supplier, then patch up the parapet until spring/summer when I will do a proper job with angle tiles.

One ladder related question; at the front of the house I can line the roof ladder up alongside the parapet by hooking it over the ridge but at the back of the house there is no ridge as the parapet runs along the 'ridge', so is there some sort of adaptor to hook onto the parapet??

Many thanks
 

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