Removal of cement render and re-render in Lime - timber framed house

[Chinny]

Hi,



We’re planning to do some works on the exterior of our building that involve removing about half a metre of the cement render from the base of the side of our house (photo of side below) in order to repair the decayed timber at the base of the building as a result of moisture.



In an ideal world we would remove all the cement from the outside but I think that will be too expensive for us currently. First question is, how obvious is the difference in materials going to be i.e. where the lime will meet the render. I’m concerned that we are going to pay a large sum of money and the house end up looking odd as a result. At the minute its painted with this masonry paint https://www.brewers.co.uk/product/BN041755F/Suffolk+Pink but will need to do a lime wash on the new render. I could scrape off the old paint from the rest of the cement and put a lime wash on that to try make it look closer. I’m under the impression this is a pretty common job that happens to a lot of these properties that were covered in cement back in the 50’s/60’s. Does anyone have any similar experiences or photos of work they have had done?



My second question is regarding a French drain. The surveyor recommended installing a French drain along the side of the house as the tarmac driveway contributes to water making its way towards the sole plate. I’m tempted to remove the entire driveway and replace with stone and gravel. Would this work equally well and are there any considerations I need to think about before doing it?



Thanks in advance.
Alex

 

[Alex_]

Have you considered just removing the render that is painted black on the external side and making the property breathable from the inside? Essentially this was what was recommend to us as the external cement render is nicely pargeted as it is whereas the inside hadn't been redecorated for some decades prior to our purchase. We had to replace about 8m of sole plate in total (most along the front, some at the sides) and some of the vertical timbers but this was done mostly by removing the internal cement render and maybe only the bottom 30cm of external (which we're redoing in cement given the inside is now lime plastered from floor to ceiling). It was a good opportunity to replace not very good 80s insulation with wool where we could. The builders managed to preserve a lot of the clay bats as well. I can post pictures later, and they will finish the outside next week.

 

[Cubist]

I think Alex has a good idea there. Removing the cement render to just above the cill plate - which you would have to do anyway - and perhaps leaving the cill and below completely exposed would allow the plate and the wall to breathe much more effectively. Once any repairs to cill are completed you can always reconsider and go with your plan to use a lime mortar render over the lower section. However, you would need to fashion a slight overhang on the bottom edge of the cement mortar render to operate as a drip edge for water running down the wall. Lime and cement renders do not bond well at the point of any interface between them.

 

[Alex_]

I just saw your other thread. Although your property is a century or so older, it looks like you have very similar issues to us with cement render on wire mesh and a bituminous layer with dodgy rockwool type insulation, given you're not that far away I suspect it was subjected to the recommended treatments of the time, in which case I even more strongly recommend my suggestions. We also have a french drain running around most of the property (its detached) that has been dug deeper at the front as part of the above works. I can't say how well it worked, but the brick foundations were in great condition with almost no spalling and only small parts of the top, above ground layer needed replacing, so it might have helped somewhat.

 

[Chinny]

I agree, the thing I think that has caused the most damage is the interior pannels that were foil lined and then stuffed with rockwool. The room above has the original daub in between and those timbers are perfect. I think if we just removed all the interior pannels and replaced with a more suitable option that would prevent further damage. We are going to approach it from the outside as the builder said it would be easier to do than propping the house up and replacing from the inside. I think the plan is to repair it rather than replace it even though its not original. I think doing the smallest amount possible makes sense in terms of exterior render, I dont want to be a martyr. Its also semi-detatched so would have an impact on the asthetics of the building as a whole since it was one house originally.

Did you completely replace the vertical timbers with new ones or better condition old ones?

I have submitted a listed building consent application for the works, hopefully they dont hold us up too much.

Look forward to seeing the work you had done Alex.