Rendered Cob Wall

[Rachel]

Hi
My name is Rachel and Ive recently purchased a part C16th & Victorian cottage. The front part of the house is Cob and the previous owners had it rendered with some type of cement/pebble dash. Although it appears sound (but very dirty looking) I would like to know what is underneath or should I leave well alone. The other problem is that the house has no frontage and therefore Im unsure as to how I would go about getting permission to carry out any works whilst dodging the traffic. Any advice would be appreciated.

 

[CHRIS]

I am not sure about the cob wall but should you need scafolding etc that is on the road you should contact the local highways people, The scafolding people should be able to arrange permits etc but ask first. The local inspector will come and have a look once it is set up.

This can take a while so plan ahead, you will have to have footpath diversion signs and flashing lights etc (hope it is not next to your bedroom!!!)

 

[biffvernon]

Rendering cob with cement is not a smart move as it does not allow the cob to dry out in the manner of lime render. Entrapped moisture can result in dramatic failure of cob.

But do get some on-site advice from someone who knows before hacking off all the cement. There have been cases where the cement is all that holds up whatever is behind.

 

[NT]

Cement on earth walls is a real no-no and can lead to collapse. Cement tends to cause build up of water within the earth, and when the earth content turns to mud it doesnt hold houses up very well.

As Biff says, it is possible for cob to have deteriorated to such a point that the render is all thats holding the building up. Consequently its important to remove only limited patches at a time, proceeding further when the dampness of the cob is low enough for it to be structurally sound.

Of course yours is unlikely to be in such a borderline state, but since it can occur, precautions are called for.

Suggest googling for earth houses, I've seen a couple of good sites but cant find the urls. Also you'll need someone with structural expertise specifically in earth buildings. I imagine that wont be too common.

I trust your survey picked up this structural problem.


NT

 

[Maris]

The cob walls on our house were cement rendered in the mid-1970s. it has taken 30 years for deterioration to really become apparent, but they do need a lot of work now!
Something that would probably help/ inform you is attending a cob or lime day. Places like J&J Sharpe and Mike Wye in Devon do these. They will give you advice, and contacts should you decide to carry out any work.

 

[Rachel]

Thanks very much for all your comments.
It looks like I'll have to book on to a course sooner rather than later.
Ill keep you posted.