How to takle roof problem

A couple of years ago we had someone replace the lead valleys on our roof but I think the cerment mix he used was too sandy and now all the pointing is starting to crumble and wash into the gutters. So I need to get onto the roof (only low - a bungalow) and repoint them myself.

A couple of questions: How am I best to tackle this job (see picture below) - a roof ladder over the extension part of the roof would allow me to work on the lower

1/3 of the valley but I just can't see a safe way of getting access to the upper 2/3 of the valley; is there anywhere on the roof it is safe to tread without a ladder?

What sort of mix do I need so that the mortar is weatherproof?

Pic of roof in question:

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Reply to
gruneecaig
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That roof has a shallow pitch, and so is easy to walk up and work on. The tiles are OK to tread on, but when you take them off to rebed the valley tiles, tread on the laths where they are nailed to the rafters.

Hiring a small tower will be easier than going up and down the ladder, but is not really essential as once you're on the roof you can work and stack materials.

Don't repoint - you will be back up there in a couple of years time. You need to take the valley tiles off and rebed them. Use a a stong mix (1:3 or 1:4) and ensure you mix it just wet enough to be workable, and when it is setting, trowel the mortar smooth to give it a tough weathering face - that is more important than the mix strength.

I would use a little sharp sand (3:1:1) to make a tougher mix than just building sand

dg

Reply to
dg

As this is a lead valley, it will be supported by timber layboards. Tie the ladder to the guttering (or fascia board via an eye hook(s) at the bottom of the valey and stand on the lead which looks plenty wide enough for size 10's. Choose a dry day obviously.

Good advice. Mortar and lead don't go well together, similarly mortar and wood. Modern GRP valley units have a sanded line to bed onto. The correct method is to fit 150mm wide cement fibre strips on top of the lead, and bed on to that.

-- WSB

Reply to
West Stand Bowler

I did mine just by walking on the roof -- angle looks like about 30 degrees which is quite easy to walk on. I would suggest a scaffold tower positioned at the bottom of the valley to work from.

Lafarge recommended to me 3:1 when using their cement with plasticiser included. You can add a little waterproof-PVA (not regular PVA) to improve the bond.

To make it bond to a GRP (plastic valley), paint the valley (just the area to be mortared) with a slurry of cement/waterproof-PVA/water in a 2:1:1 ratio, and apply the mortar whilst the slurry is still tacky. I don't know how necessary this is with lead.

Start at the top, doing both sides together, and work down (or do one side and leave it a week or more before doing the other side). Otherwise you will damage the work when walking on the roof.

A properly constructed valley is weatherproof without any pointing, unless there's an extremely strong gale. However, failed pointing can redirect the water inside the roofspace.

Reply to
Andrew Gabriel

I've a similar roof with valleys, possibly slightly less slope (22degrees) I had to replace the valleys as the builder had used a single piece of code3 lead for the 4 metre long valley. I just walked on it.

I used 3:1 with plasticiser. I also used 5:1 with plasticiser on a verge I may need to remove about 4 years ago. It seems as solid as the rest. I haven't got round to removing it yet (to replace the undercloak and felt, which was bodged originally).

Reply to
<me9

I had to split a 150mm strip into 2 75mm strips to fit the space. It has worked fine. It is important to bed first, and if necessary pointing up after th bedding has hardened, but not dried out.

Reply to
<me9

wrote in message news: snipped-for-privacy@h48g2000cwc.googlegroups.com...

Access on to the roof, place the ladder at least 3 tiles away from the bottom of the valley. Push up 2 of the second row of tile, this will enable you to take out a tile on the bottom row and reveal the tile lath so you can tie the ladder. From the photo the roof pitch is flat enough to walk up. Don't walk up the roof on the valley cut tiles, try to keep at least 2 tiles away. When you get to the top of the valley kneel down with one knee in the centre of the valley on the lead, the other knee on the tiles. The first row of full tiles that go straight across the top of the valley, push two up, one either side, to reveal the first cut valley tiles. Start to remove the cut tiles, removing the old mortar, and numbering them as you take them off, e.g. number one, then number two as you go down the right-hand side. Stack all the tiles on the roof well away from the valley area within two arms length reach. Leave the old loose mortar in the valley as you work down to the eave, this is cleared out at a later stage. To do the left-hand side you will have to take off the ridge to reveal the top row of tiles, then do the same as the opposite side. When all the tiles have been cleaned the next step is to remove the old loose mortar from the lead and out of the valley area. when all the loose mortar as been removed brush all the loose smaller dirt out to leave the lead clean. If the lead as been layed correct, there should be a fibre cement strip held in with lead type adhesive to hold it in place and the outter 25mm or 1"of lead turned over the outter edge of the fibre strip. Under no circumcises should any nails be used to hold the strip in place, this will cause capilery action through the the nails, no nails should penitrate the lead. If there is no fibre strip and no turn back on the lead the valley is suspect to capillary action where the mortar joins the lead. Lead expand & contracts leaving an air line gap between the two. This causes capiliery.

Lay a bed of mortar, 2 sand 1cement stiff mix, about 50mm or 2" high x 75mm or 3" wide about 600mm or 2 feet up the valley from the bottom, keeping the mortar about 50mm or 2" away from the outer edge of the valley, lay the first cut tile on top of the mortar, continue to the top. When one side is complete just scrap off any surplus mortar that as ouesed from under edge of the tiles. Do not push any mortar back under the tiles as this will only sag and also you will push the mortar over the edge of the lead on to the underlay. Carry on with the other side in the same way. Rebed the ridge. By this time the mortar under the valley tiles cuts should have gone off. add a little water to the mortar you have left over or mix a bit more 2 sand1cement soft mix. Run your trowel down the edge of the valley mortar just to take off any protuding bits. With the mortar you have eithr mixed or have left spread this to the vertical face of the bedding, making sure you clean out the joints of the valley cut tiles. With a small hand brush lightly clean the mortar off the lead. Hope this helps. It easy to do than to explain. Keith

Reply to
keith_765

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