Rendering/Pointing

[dandy010101]

I have a few problems with the rendering on the side wall of my house, I've read several of the discussions on the subject here, but it's not exactly clear to me….

I have an end terrace house built around 1880. When it was built it was mid terrace, but the house on the end has been knocked down, leaving mine now as the end terrace (this was done about 40 years ago). As such, the front and back of the house have an outer leaf of stone, there is also an inner leaf of brick - the exposed external side wall is just a 9in thick brick wall, which was obviously originally intended to be just an internal wall. The outer stone leaf at the front and back is not knitted into the brick exposed side wall (it is just knitted into the inner brickwork at the front and back) hence a concrete render has been applied to the side wall.

The house is badly damp due to elevated ground levels where the original end terrace used to be. I have now lowered the ground levels to rectify this problem and also removed some of the footings of the knocked down house to properly lower the ground level. This has left me with several problems.

Firstly, the concrete render on the side wall is cracked in places and blown in others, it is also now about two foot of the bottom of the wall as the ground has been lowered. Obviously the render needs to be made good, but I am concerned that the solid concrete render is making the damp worse as it can't breath – what are the appropriate materials/methods for fixing up the render? Would I be better of removing the render from the whole wall and applying a more breathable/lime based render, in keeping with the mortar used on the house in the first place?

Secondly, for the area where the ground has been lowered, I now have exposed brick work that will in due course be covered by the new render. However, first of all I want to knit this wall in with the stone work and re-point it, as the wall was never intended to be external. Should I be using a lime based mortar for this as was originally used on the house, or, given that it is a brick constructed side wall and only stone at the front and back, should I use a cement based mortar? The wall is quite damp already, so I don't want to treat it and lock moisture in.

Any help/thoughts would be greatly appreciated!

 

[countygardens]

sorry, wont touch this one with a 10' pole. Just look at the mess of the thread called 'blown render please help'. If you have a spare month to read all the ranting and raving then you will still be none the wiser

 

[dandy010101]

I quite understand countygardens - I get the impression your not the first to opt out of the discussion! I Got about half way through it myself and thought I'd just try posting my situation than try to work it out from other people's problems...

 

[countygardens]

For your info, there have been quite a number of other threads in the past regarding render that havent ended up such a mess. Have a look down the list and you might find some good advice.

Good luck

 

[Nige F]

As usual I look from another angle .Who owns the "plot" where your neighbouring house used to be I would check out and I would also assume they have responsibility .under the party wall act Better still, if you had used the ground for 10 yrs you could claim adverse ownership Legal Advice for me From Citizen`s advice first. IF you own it get a hous in there quick and make a few bob.

 

[TexMex]

Personally, I'd suggest that you build another skin up the flank of the house. You could then get all of the benefits of a cavity wall back. Although it's a bigger job than rendering, at the end of the day, It would be a more permanent solution. You could also choose the same type of stone, as has been used on the front, to give a completed appearance.

 

[TexMex]

sorry, wont touch this one with a 10' pole. Just look at the mess of the thread called 'blown render please help'. If you have a spare month to read all the ranting and raving then you will still be none the wiser

Crikey. There's 16 pages of it. I haven't the time to read all that. That's going to be the most well planned rendering I've ever heard of. Can you cut right to the chase and give us the commitees findings

 

[countygardens]

sorry, wont touch this one with a 10' pole. Just look at the mess of the thread called 'blown render please help'. If you have a spare month to read all the ranting and raving then you will still be none the wiser

Crikey. There's 16 pages of it. I haven't the time to read all that. That's going to be the most well planned rendering I've ever heard of. Can you cut right to the chase and give us the commitees findings

Well they seem to think that they are all correct!!! Thats pretty much the findings!!! Nightmare.

 

[Freddie]

I'm afraid we have to agree to disagree---whatever you do dont mention pva

As regards your problem---unless you have a cavity i am afraid you will always be having or in danger of having a problem with damp.

Any bad render will have to be taken off and replaced, but if you do go for the cavity and stone look, this will look a lot better and no render and no damp

 

[legs-akimbo]

You need to strip back to the bare substrate, set a bellcast bead or form one with timber 2"x1" 150mm above the d.p.c. There are alternatives in external insulation batts that can be mechanically fixed to external walls then covered with pre mixed render coats. May be an idea to black jack below the bellcast (plinth) and dash sharp sand against the second coat of B.J. and allow to dry before rendering this also.
Certain persons suggest using PVA ...do not ...if in doubt refer to technical details which explicitly state "Not for external use"
Do use waterproofer in the top coat.. If in doubt refer to technical detail which explicitly states for this to be done.
Do employ a plasterer who is capable of undertaking a large expanse and will not divide up your gable end into neat little sections with expansion strips so as to potter away on wincy little areas one at a time.
You can not make a silk purse from a sows ear...bite the bullet and get the job done right once and once only, Dont spoil the ship for an apeth of tar!

 

[jbonding]

i would go with legs on this, i also wouldnt use pva as a bonding agent neither like a certain person suggests whoever that is. I would definetly refer to the technical data, do not employ one plasterer who is not capable of undertaking a large expance without breaking it up into sections because they cant handle a waterproofer in the scratch coat, employ a decent gang of men. i would honestly go with freddie on this, the rendering is gonna cause you problems due to the 9" wall so building another skin of stone even though it might be expensive, in the long run will save you money and stress. The heat loss would be reduced massively, the building would look complete and wouldnt draw any attention off the next buyer.

 

[joelincs]

I have a few problems with the rendering on the side wall of my house, I've read several of the discussions on the subject here, but it's not exactly clear to me….

I have an end terrace house built around 1880. When it was built it was mid terrace, but the house on the end has been knocked down, leaving mine now as the end terrace (this was done about 40 years ago). As such, the front and back of the house have an outer leaf of stone, there is also an inner leaf of brick - the exposed external side wall is just a 9in thick brick wall, which was obviously originally intended to be just an internal wall. The outer stone leaf at the front and back is not knitted into the brick exposed side wall (it is just knitted into the inner brickwork at the front and back) hence a concrete render has been applied to the side wall.


The house is badly damp due to elevated ground levels where the original end terrace used to be. I have now lowered the ground levels to rectify this problem and also removed some of the footings of the knocked down house to properly lower the ground level. This has left me with several problems.

Firstly, the concrete render on the side wall is cracked in places and blown in others, it is also now about two foot of the bottom of the wall as the ground has been lowered. Obviously the render needs to be made good, but I am concerned that the solid concrete render is making the damp worse as it can't breath – what are the appropriate materials/methods for fixing up the render? Would I be better of removing the render from the whole wall and applying a more breathable/lime based render, in keeping with the mortar used on the house in the first place?

Secondly, for the area where the ground has been lowered, I now have exposed brick work that will in due course be covered by the new render. However, first of all I want to knit this wall in with the stone work and re-point it, as the wall was never intended to be external. Should I be using a lime based mortar for this as was originally used on the house, or, given that it is a brick constructed side wall and only stone at the front and back, should I use a cement based mortar? The wall is quite damp already, so I don't want to treat it and lock moisture in.

Any help/thoughts would be greatly appreciated!

Damp either travels in horizontally (sort of) or rises. To stop it rising you must have a vertical DPC, this can be chemical as you know and inserted into an existing wall.

To stop the vertical entry the outside render must not have any flaws. I wouldn't use a lime mix. I might take all the rendering off and start again. I might use a patent waterproof base coat first. I migt add a water proof additive to the top coat of render. I might repair the wall and apply a masonry waterproofer and renew every 5 years. I might repair the wall and apply a good masonry paint.

I might call in a damp proofing firm and get them to do the job and garuntee it.

rgds joelincs