Cement

Got to go on roof in morning. Can anybody give the correct cement mix for fixing ridge tiles and how much waterproofing to use. Ta very much!

Reply to
sploop
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4 to 1. No water-proofer as it is not needed and tends to blows the stuff off.
Reply to
Michael Mcneil

NT

Reply to
N. Thornton

1:1:6 what ? (cement:fine sharp sand:soft sand I presume ?) if the OP doesn't know the difference between cement and mortar he aint gonna know what that means (c;

my son (and his lecturer) says they use a mix of 4:1 (sand:cement) for general purpose mortar as for waterproofer, it should tell you on the bottle/can

LJ

Reply to
in2minds

I think 1:1:6 refers to lime/cement/sand. Lime acts as a plasticiser and so makes the mixture easier to use. Of course, you can use straight cement/sand as also advised, but that needs a plasticiser like PVA or the proprietary stuff to make it handle as well as the lime/cement/sand mixture. I believe squeezy is frowned on asa cheapo plasticiser. Maybe your waterproofer has plasticising properties?

Andy.

Andy.

Reply to
andrewpreece

I'd be inclined to use a suitable mastic. No matter what mortar mix you use, it always seems to crack and bits fall out. Not surprising considering that most roofs are supported by timber which will move with the seasons.

Reply to
Dave Plowman (News)

Thanks all, however more confused than before. NT. I thought your contributions before quite helpful. So what went wrong this time? 1:1:6 WHAT. Sugar, coffee? WHAT? If I already knew I bloodywell wouldn't be asking. Anyway thanks to those that did answer with their help.

Reply to
sploop

It means Cement:Lime:Sand (or is it Lime:Cement:Sand -- never can remember;-)

Personally, I would not bother with Lime here, I would just use a

1:4 Cement:Sand mix.

I would add some outdoor/exterior grade PVA to the mix -- something like a teaspoonful per 1-2 shovel loads of sand. This will improve the adhesive properties of the cement, which is otherwise not brilliant. Mix a tiny amount of water into the PVA first, and then mix it with the rest of the water before adding the water to the mortar, otherwise it's not easy to mix it into the mortar uniformly. If there's any danger of it freezing or even a frost in the several weeks following application in such an exposed position, you'll need an anti-freeze additive for mortar too.

Reply to
Andrew Gabriel

I think he means lime: cement: sand. Unecessary.

4:1 dryish (that is: not too wet) will be waterproof and weatherproof enough and go off quickly without cracking. It is ideal on a roof.

By the way, you only need dollops under the end of each tile to stop them rattling. None goes in the overlap to cement them together. You might want to point them up afterwards -that's up to you.

Reply to
Michael Mcneil

Cement:lime:sand. It's a classic mix that allows some movement. Some say you can replace the lime with plasticizer or even some washing up liquid, but although this may make the mix as easy to work, it doesn't give the same flexibility when set.

Reply to
Dave Plowman (News)

fair point. Cement:lime:sand.

Roofing isnt really a general purpose mortar job. It would still work though, just better to use a weaker mix.

yup

NT

Reply to
N. Thornton

When you buy lime to use in a cement:lime:sand mortar mix, what kind of lime do you ask for and how is it used?

Reply to
Cycle

of lime do you ask for

just 'lime'. What you'll get is hydrated non-hydraulic lime.

mixed in with sand and cement, typically 1:1:6 by volume. Dont use

1:2:9 mix, as studies have shown it fails prematurely. Lime adn cement works well but only in some proportions; some other mixes will fail.

BTW concerning 1:4 vs 1:1:6, both work, but 1:1:6 is weak enough that if the roof moves a bit, the mortar fails rather than the tiles and slates breaking, which is preferable. But either will do the job.

NT

Reply to
bigcat

A relative that lays bricks for a living tells a marvellous story of a somewhat intellectually-challenged workmate whose every working day started with an increasingly desperate search for eight buckets...

Reply to
Sam Nelson

Thank you.

Cycle

Reply to
Cycle

Reply to
sploop

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