How to fill this? 31 January at 6:38PM in In my home (includes DIY) MoneySaving 7 replies 473 views

ck7ah

Hi, the cement from the extension roof has started to come off. 
As it's a small amount, I was wondering what the best way to fill this and what cement I should us?

mi-key

Normal mortar should be fine. Screwfix do tubs or even ready mixed. Because of it being vertical I would mix it up fairly dry so its not too sloppy so it doesn't sag when you put it in - may even be worth doing in a couple of layers rather than all in one

stuart45

Most roofers use 3/1 sand/cement mix. Sand should be 50/50 sharp/building. Just a touch of plaz. Black dye is usually added to stop it drying too white.

ck7ah

mi-key said:

Normal mortar should be fine. Screwfix do tubs or even ready mixed. Because of it being vertical I would mix it up fairly dry so its not too sloppy so it doesn't sag when you put it in - may even be worth doing in a couple of layers rather than all in one

Thank  you for the information, it was actually done last March by someone but some of it has come off, i will try and see if he will come back and redo the small patch, else i will do it myself. 
Will this be ok to use - Bostik General Purpose Mortar Grey 5kg - Screwfix
Would i need to put anything else inside the gap or will mortar suffice and go deep in as possible?

stuart45

You can use it if you like, but it's not the correct mortar for pointing up the verge.

ck7ah

stuart45 said:

You can use it if you like, but it's not the correct mortar for pointing up the verge.

Would it be what you recommended?

stuart45

That's the mix recommended by the NHBC. It's best to stick some pieces of broken tile in when you point up. A bonding agent like SBR/cement pasted on the old mortar behind will help the new bond to it.

mi-key

ck7ah said:

mi-key said:

Normal mortar should be fine. Screwfix do tubs or even ready mixed. Because of it being vertical I would mix it up fairly dry so its not too sloppy so it doesn't sag when you put it in - may even be worth doing in a couple of layers rather than all in one

Thank  you for the information, it was actually done last March by someone but some of it has come off, i will try and see if he will come back and redo the small patch, else i will do it myself. 
Will this be ok to use - Bostik General Purpose Mortar Grey 5kg - Screwfix
Would i need to put anything else inside the gap or will mortar suffice and go deep in as possible?

Yes you can use that if you want something simple. I have actually used the same stuff for making repairs to some concrete window sills, and it worked very well.