Forums

Forums
Sustainable Sidetra...
Well & Truly Off Th...
Extensive plaster c...
 
Notifications
Clear all

Extensive plaster cracking after heat pump installation - thermal cracking? subsidence?

 
Well & Truly Off The Grid
Last Post by Flowboy 3 years ago
4 Posts
4 Users
2 Reactions
3,110 Views
RSS
 HJBHome
(@hjbhome)
Active Member Member
12 kWhs
Joined: 4 years ago
Posts: 3
Topic starter 07/01/2022 11:03 am  

Hi,

Perhaps a long shot, but wondering if anyone has had issues with thermal cracking following a change of heating system. We’re in a 1930s converted bungalow with old plaster walls and ceiling. We switched to a heat pump from a combo boiler in August and had underfloor insulation installed at the same time which significantly reduced draft and damp from the foundations through the wood floors. We had some ceiling cracking prior to this, but have had widespread and quite worrying cracking in walls and ceiling this winter. We’re property surveyed as we are worried it could be land slip or subsidence, but I’m wondering if a more benign explanation is possible in terms of thermal / moisture changes related to the new heating system?

Would be really interested if anyone’s had a similar experience.

Thanks

 


   
Quote
 batalto
(@batalto)
Famed Member Member
3655 kWhs
Joined: 4 years ago
Posts: 1091
07/01/2022 11:27 am  

if there was a lot of damp in the lower walls and foundations the cracking could be caused by the drying out. How large are the cracks?

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
ReplyQuote
 Kev M
(@kev-m)
Famed Member Member
5606 kWhs
Joined: 4 years ago
Posts: 1276
07/01/2022 11:34 am  

I suspect also that it's the floor insulation and reduction in damp.  That sort of thing happens when you mix modern insulation/damp proofing with the original in an old house. I suspect it will settle down and at worse you'll need to do a bit of filling.  But make sure you use the correct sort of plaster/filler (same as the original) if you do.   


   
ReplyQuote
 Flowboy
(@flowboy)
Active Member Member
0 kWhs
Joined: 3 years ago
Posts: 7
08/01/2022 8:51 pm  

@hjbhome   Before you open up a can of worms re. potential subsidence - insurance claims, underpinning etc 😱.

Unless the cracks are large enough to see into the brickwork, or they are actually following the brick courses to some extent, the only way to be absolutely certain would be to hack off the plaster on the worst wall, (or perhaps an affected wall in a small room to look at the brickwork - then you only have a smallish area to re-plaster...) External signs of cracking along brick courses would be more worrying - although can also be caused by rusting cavity wall ties.

However... When you say 1930's property, I would think you quite likely still have a lot of natural lime plaster. This "breathes" - takes up & gives out moisture - adapts to humidity levels. How much it has been able to do this fully naturally, I suspect will have been reduced by the layers of modern emulsion or other paints, partially sealing the walls in modern times. They may have been breathing to some extent but taking much longer to do so with the modern paint coatings.

Your serious thermal improvements & draught reduction are no doubt keeping more heat in the property than you previously managed. It may be that the sudden change in air temp / dryness - without the previous possibly slightly damp draughts, may have caused the plaster to dry out very rapidly. Hence the cracking. There are a number of lime & eco specialist companies that supply fillers that might do the job. A bit more expensive. On the other hand if there are innumerable coats of modern paints then a modern flexible filler might be ok, I would leave it for some time until the cracking activity has stopped.  If you still have lath & plaster ceilings then I should think the same would apply - they do become more vulnerable with age anyway - plaster detaching from laths.

I would think that drying out below floor / dpc level would be unlikely, as the drying will surely only / mostly be in the occupied parts, unless you also have a heated basement. If you can see your basement / underfloor walls they might reveal if the cracking has more worrying implications or not.


   
👍
2
ReplyQuote
Forum Jump:
  Previous Topic
Next Topic  
Share:

Join Us!

Heat Pump Dramas?

Thinking about installing a heat pump but unsure where to start? Already have one but it’s not performing as expected? Or are you locked in a frustrating dispute with an installer or manufacturer? We’re here to help.

✅ Pre-Installation Planning
✅ Post-Installation Troubleshooting
✅ Performance Optimisation
✅ Complaint Support (Manufacturer & Installer)

👉 Book a one-to-one consultation now.

Latest Posts

x Powerful Protection for WordPress, from Shield Security
This Site Is Protected By
Shield Security →