Oh no, it's another lime plastering question.

[overlander matt]

Hi,

After a few weeks digging up floors to put in insulation and underfloor heating and running new external drainage, it's time to get back to some plastering. This time, we are starting with brick walls that have had all previous plaster removed. Some of the oldest sections had the internal brickwork painted but were later plastered - these sections seem to have had the faces of the bricks chipped to provide a key for the plaster. Most of the other bricks are bare so should be ok to plaster onto. I am hoping there is no further preparation required for these areas other than wetting the walls in advance.



Another area in an adjacent room (the right hand side of the photo) has had the internal brickwork painted with a shiny paint that looks a bit flaky now the old gypsum plaster has been removed. There were signs of damp in this room that I hope will be solved with a breathable plaster. I plan a good scrape and possibly an application of a primer such as DG27.

We plan to mix sharp sand with Secil NHL3.5 for the first and second coats rather than use a premixed sand and lime mixture as I have elsewhere for smaller areas. Any recommendations or advice would be much appreciated.

Matt

 

[paulc]

A silicon carbide rubbing block will probably shift much of the paint and provide a suitable key for any plaster. Worth spending £5-£10 to find out rather than £xx on DG-27.
As for the plaster, I'd mix in a good hand full of 20mm screed fibres (available from the likes of Jewsons, Travis Perkins, and other builders merchants). Being polyester, they won't be affected by the lime like animal hair would be.

 

[Zebra]

I'd fill those larger holes first - like pointing - rather than relying on the first coat to do so. That huge vertical joint mainly, otherwise the first coat will be very thick in places.
Also, sharp sand only? No soft?

 

[Flyfisher]

Yes, I wondered about that ‘joint’, which is hardly a joint at all. I’d be tempted to embed some ‘helifix’ strips across the gaps to strengthen the joint. Not expensive, can get them in Screwfix, and no need for resin fixing either, just rake out the existing mortar and then re-point over the helifix rods.

 

[overlander matt]

Thank you for your thoughts on this fairly basic plastering question. It took a while to get enough sand and lime to do the first coat. That is now on and drying and we will get on with a second coat soon. The brickwork was pretty uneven so it has been a challenge to try to straighten them out as best we can.

As for the large crack, I have avoided that so far! There will be an internal door frame to go in there whenever I can find some timber to make one. That will cover it up but maybe some sort of repair is wise.

The next decision to make is how to finish the reveals around the sash windows - the wall is 3 bricks deep so we are effectively left with a reveal of around 120mm. How would you suggest I finish this? Timber in the reveal and then an architrave on the wall or a plastered reveal? There are no other examples I can follow elsewhere in the house as the other 3 brick deep walls all had a different style of window and shutters.

Thanks in advance for any good ideas.

Matt

 

[paulc]

Georgian house from memory ?
(Well, I cheated and looked up some older posts...). Timber around the reveals with some architrave would probably be in keeping with the period. But finding timber of sufficient width without any cupping is going to be the hard pert. I'd probably go and find some narrower planks and glue them together which is what I did with a window sill that I needed to replace.

 

[a twig]

Routing grooves into the back of the timber (a la floorboards) can help prevent cupping if you wanted to do it in one piece.

 

[Abi Cott]

Not original, new window replicating the old one and I suspect the specific architrave was added in the Victorian era rather than the original which would have been plainer, but for a concept image I thought it might help. House dates to 1829

 

[overlander matt]

Thanks for your thoughts on this one. The house is originally Georgian although the section with these windows was, I had thought, a later Victorian add on but further probing suggests there was an earlier structure that was probably modified in Victorian times. General consensus sounds like timber is the way to go. I had struggled to find any timber in the current time of lockdown but our local merchant has just reopened and will deliver some planed timber to line the reveal. There is one other window in the house that has a similar approach that I had forgotten about so I copy that. The reveal is only around 120mm so the risk of the timber cupping is less than in could be.

I never seem to have enough time to post any pictures these days. These old houses seem to take up a lot of time... anyway, here is the before and after view from the outside: