Repointing this internal wall - advice please (lime mortar)

[philv]

Hi,,

we have a small Victorian terrace.

The lime plaster behind the radiator in the front room had blown so it was removed.

There's a little lime mortar missing as shown in the photos.

Should i just fill the gaps with nhl3.5 lime mortar or should the old mortar be completely removed first?

Do i have to wait 90 days for it to dry before replastering with lime plaster or can that be done straight away? (does the answer differ depending on the answer to the previous question?).

Also, i'm a bit concerned about rehanging the radiator.
Is it ok to put normal cement mortar on the area where the radiator brackets screws are (for strength)?

Thanks

 

[aockenden]

Small little areas of cement aren’t going to ruin your house, so if it makes you feel more secure hanging the rad then go for it.

No need to remove the old mortar (unless it’s super crumbly or degraded). You can just pack some new lime mortar into the gappy areas. NHL 3.5 is probably fine, NHL 2 is more appropriate but for those small gap areas its not a huge deal. If 3.5 is what you have and are comfortable using, then go for it.

Once you’ve packed out the gaps, give it a day or two to firm up via the hydraulic set, then plaster it. Absolutely no reason to wait 90 days before plastering.

 

[paulc]

It would be worthwhile putting some insulation on that bit of wall. A parging coat of plaster first to level the wall off, then some cork or woodfibre insulation. Finish off with a skim of lime plaster. The window board would need extending. If it is uPVC (which it looks like it might be), solid wood would look much better..

As for fixing the radiator to the wall, using brown wall plugs is putting way too much trust in them. That radiator is going to weigh something in the order of 22-25Kg, so it needs solid fixings. I've used grey wall plugs in the past with 6mm coach screws. With one particularly heavy radiator, m6 wall bolts with a generous squirt of resin-fix was needed (close to the edge of a brick, and I'd drilled in to the frog). Those little blighters are not coming out in a hurry

Somewhere in my box of bits, I have a bag of heavy duty fixings that came with a radiator. Ping me a message if you want them.