cement render??????

[pete32]

Hi everyone,

We own a 17th century cottage and have been renovating it for the last twelve months, when we moved in their were many jobs to undertake the main one being that the sole plate had rotten away due to high moisture levels after being tanked in the 80's, we have had the internal walls plastered in lime to allow the new timbers to breath. We now have a big decision whether to remove the cement render from the front of the house as this is badly cracked near one window, the house bowes out in the middle at the top and I am worried that the house may fall down when the render is removed, is this really possible or am I worrying over nothing.

 

[MdB]

Whats under the render? i.e. what is the wall made of? If its cob then there is a good chance it will fail if it is water saturated underneath. I couple of people have mentioned cob failing when the cement render has been removed so if this is your construction you need to get the moisture out before removing the cement and proceed very very carefully. Others will comment on other constructions.

 

[arthurw3]

Assuming it is a brick construction, you need to drop a plumb line from the top of the wall to the bottom and plot out the amount of bow in the walls at various places along the wall. If the centre of the wall is bowed more than the half the width of the wall, i.e. the centre of gravity of the wall is outside the foundations the wall is unstable. If the centre is still over the foundations it may well be stable, especially if it has not suffered movement recently. Check how the leaves of the wall are bonded together, and how the floor and ceilings are tied to the wall and the partition walls to the outer wall. If there is a lack of bonding, this needs to be remedied with something like helifix pins and metal straps between the wall and floors and ceiling. If the bonding between the walls etc. is satisfactory it is probably safe to remove the render. However if there is any doubt, a structural engineer with experience with whatever construction you have will be needed to advise.

 

[pete32]

thanks for the reply, I have been told that it is all timber frame with lath and lime internal and at the moment lath and cement render on the outside. The wall has bowed out about 1 foot from the centre of the property and about an inch in the corners. There is a large 32mm steel bar running from the back of the chimney breast right through the chimney and drilled through the centre beam to the front with a large plate and nut

Whats under the render? i.e. what is the wall made of? If its cob then there is a good chance it will fail if it is water saturated underneath. I couple of people have mentioned cob failing when the cement render has been removed so if this is your construction you need to get the moisture out before removing the cement and proceed very very carefully. Others will comment on other constructions.

 

[Nemesis]

Timber framing and cement render are very bad ideas indeed.

Timber moves and it can be very out of plumb and still not collapse, but if you don't know what you are doing then I would suggest getting some advice from someone with expertise with historic buildings as to how to proceed.

Is the building listed?



[Open Image] [Hosted by PhotoGalaxy.com]

Some of Stephen's article here is relevant:

http://www.buildingconservation.com/articles/mortgage/mortgage.htm


and here's an advice sheet from Andrew:

http://www.breckland.gov.uk/timber_frame_advice_sheet.pdf



[Open Image] [Hosted by PhotoGalaxy.com]

 

[pete32]

Yes the building is grade II listed, all beams at lower level have been replaced and the sole plate sits on bricks about 2 foot from ground level, maybe I should remove some of the cracked cement and have a look at the interaction between the roof and top level beam.

Timber framing and cement render are very bad ideas indeed.

Timber moves and it can be very out of plumb and still not collapse, but if you don't know what you are doing then I would suggest getting some advice from someone with expertise with historic buildings as to how to proceed.

Is the building listed?



[Open Image] [Hosted by PhotoGalaxy.com]

Some of Stephen's article here is relevant:

http://www.buildingconservation.com/articles/mortgage/mortgage.htm


and here's an advice sheet from Andrew:

http://www.breckland.gov.uk/timber_frame_advice_sheet.pdf

 

[arthurw3]

I obviously don't know what the location is like, but have you considered the danger if lumps of this cracked concrete render fall onto anyone?

 

[Nemesis]

Before removing anything, I'd talk to the CO - you may require LBC.

Your CO may also be a very informed source of advice.

 

[Gareth Hughes]

[Open Image] [Hosted by PhotoGalaxy.com]


where's that? - no nonsense about rights to light or spoiling the view there...

 

[MdB]

where's that? - no nonsense about rights to light or spoiling the view there...

I'll take a wild guess at Windsor (not that I have ever seen that building)

 

[lordmulberry]

Yes. It is Windsor. The building is next to the Guildhall where someone famous once got married.

 

[MdB]

Its the "Crooked House of Windsor" aka "Market Cross House" c 1718.

(I wonder how the door opens...)

 

[Nemesis]

Yes - and last time I was in had no problems opening it!

 

[Craig]

Hi Pete32 - hire a structural engineer who works with timber framed buildings. We used Clive Dawson from Hockley and Dawson but depends where you live.

 

[Gareth Hughes]

Yes. It is Windsor. The building is next to the Guildhall where someone famous once got married.

Oooh, yes. Elton John. :lol:

 

[middi]

A lot of oak frame buildings were cladded with a generous thick cement render external cover. In many instances this approach speeded up the frame decay, especially fast decay in the lower third of the building where more cement was added to make this area stronger and more stable. This doubled up the decay speed of the timber to the point that just frass remains of the timber are evident with no structural function. Furthermore cement render was added ( internally) to "stabilise" the building even further. On some buildings it didn't really matter if the wood rotted away, with so much cement render on wire mesh the building stood up by default. These building eventually graduated from " half timber" structures to " half cement" structures.

All because it was too much trouble to maintain the existing fabric in good repair order or carefully replace a bit of timber here and there. A lot of buildings collaps in a slight breeze when this hard render is removed. It has to be thoughtfully done.

Cement does not mix at all with timber frame buildings.

 

[pete32]

Thanks everyone

I have booked a structural engineer who has 20years experience in timber frame buildings to come around and have a look, when I get the results of his report I will post it on the forum for people who interested in similar situations.

 

[Nemesis]

There are times when someone with expertise on the spot is required. Be interested in the conclusions.

 

[sue gazzard]

I'd say you have GOT to get rid of the cement render asap & replace with lime on stainless steel or chestnut laths. I'm quite new to this but already I can't quite believe anybody let you do sole plate repairs without getting rid of a major guilty party, ie the cracked/bowed cement render!

 

[Nemesis]

Well that rather depends - if the cement is all that is holding the building together, proceed with great caution and only after seeking skilled, individual advice is my view.