Covering up cracks in internal walls

[GSJ]

Hi all,

I have a Victorian-era property (c1900, single-fronted, semi-detached, workers cottage) in Melbourne, Australia and need to tap into some of your experience with these properties in the UK.

The property sits on reactive clay soil foundations and due to this and various other factors, has experienced movement over the years. The property is not expected to collape, but eliminating movement all together is unlikely, particularly that associated with seasonal climate variations. Having said, that attempts to minimise future movement eg. by removing large trees are being undertaken.

As a result of this movement, the house has a number of cracks in the internal walls, that cosmetically do not look very nice. They are up to 10mm diameter in some areas.

A geotechnical engineers report is planned at some stage, to investigate the movement related issues in greater depth (an initial pre-purchase building inspection has already been done by an architect).

What I want to find out is what techniques people have used to cover up these cracks and improve the cosmetic appearance of these properties, in preparation for re-sale/re-rental/re-valuation?

I had this discussion in an Australian renovation forum (the link to the relevant thread is as follows: http://www.woodworkforums.ubeaut.com.au/showthread.php?t=35613) and the following ideas were brought up:

1. Get a plasterer to fix the cracks properly (the downside of this is that if there is ongoing movement, the cracks will just re-open).

2. Use a flexible sealant and paint over (some people have said this does not look good even when painted over? have to use textured paints, but it does at least allow for some degree of future movement).

3. Put new plasterboard sheeting on top (this is more flexible and less likely to crack, but will involve removing then replacing architraves/skirtings etc. so will be expensive).

4. A suggestion from a UK company was to do ´crack stitching´, a process that is described by the company Helifix (the link is: http://www.helifix.com.au/crack_stitching.html). They use ´helibars´ to structurally re-inforce/stabilise a building, and this allows for further movement. They then re-point/re-plaster/re-paint over the cracks.

5. I had another thought, what about covering up the cracks in the walls with a strong, flexible type of wall covering? Vinyl perhaps? This would be like the plasterboard sheeting option, as the vinyl may be flexible and allow for further movement??? Maybe much cheaper though? I am not sure how it would look?

Are there any thoughts/comments regarding this???
Any other suggestions/ideas???

I am running out of ideas in Australia, so am keen to tap into your knowledge base/experiences with period properties like mine

Thanks,

GSJ

 

[middi]

Is your neighbours or closeby property's experiencing the same problem or just confined to your property ?

Is the problem confined to just the interior of the property or signs of movement can also be seen on the exterior facade ?.

A few internal cracks may not mean much on the internal of an 100 year old property, especially if built on clay soil.

If these cracks are a recent appearance there may be cause for concern, if you want to cover them up so you can sell the property and not seriousely concerned about the welfare of the building , then anything will do as long as it is plastered, smoothed and painted or wallpapered.

Ideally , if the cracks are of recent appearance and cause for concern they should be professionally monitored , if it turns out to be foundation movement due to unstable clay subsoil no amount of strapping or filling is going to halt the process, and all your above suggested ideas are quite good if you want to pull the wool over someone's eyes temporarely.

If it is only " average" movement for your particular aerea then just have the walls repaired in similar render as existing and paint or wallpaper over the top, it may take another 100 years before it has to be done again.

I would keep away from flexible fillers or mastics, and use permeable breatheable masonary fillers for the really small cracks.

 

[GSJ]

Thanks middi,

The cracking problem is also seen in neighbouring properties, and has been present for many years, most of the owners have accepted the cracks and are just living with it as they love the houses and the area.

I feel there is some degree of ongoing movement due to the reactive clay soil foundations and this makes crack fixing tricky, as they seem to open up quite quickly. But, I don´t get the impression that there is anything more serious occurring. The architect who did the pre-purchase inspection felt this way too.

Needless to say, further professional review by a geotechnical engineer has been planned, as I had mentioned already.

There are cracks seen on internal and also on some external walls.

I am most certainly ´seriously concerned about the welfare of the building´, otherwise I would not have spent so many hours researching the ins/outs of cracking, nor put such a long post on several forums!

The issue here is that even once potential contributing causes of cracking are fixed, the house still lies on reactive clay soil! Things like underpinning/steel piles/resin grout injections are not things that I am keen on at present, unless there is some urgent structural problem where this may help. These techniques may be expensive and may not ´fix´ the foundations/the problem of cracking.

I am basically trying to deal with a degree of ongoing movement in the property causing cracks in internal walls that are of cosmetic concern only. Not something that is ´comprimising the welfare of the building´ (unless, a geotechnical engineers report says otherwise, of course).

Hence, I am trying to find a way to cover up the cracks (and make the property more presentable, not, ´pull the wool over someone's eyes temporarely´), that will also deal with this ongoing movement, hence the ideas suggested: flexible fillers/plasterboard sheeting/helibars/wallpaper.

Any further comments appreciated UK!

GSJ

 

[Lime]

I don't think there is any way you can prevent cracks reappearing if there is further substantial movement.
If there is a prolonged drought followed by heavy rain some movement is almost bound to occur.
The most flexible wallpaper will tear and ripple over a moving crack.

However, looking on the bright side, the cracks may not move substantially again.
Often cracks appear in the early days of a building's life and stop moving to any great extent after a while.
Most older houses built on clay have old cracks.

Many people make the mistake of just plastering over the cracks only to find that they usually reappear shortly after.
It should be remembered that once brickwork is cracked there will always be some slight movement caused by thermal fluctuation or vibration.
If the patch plaster is too thin it has no strength and cracks easily.

The most effective method for small cracks is to rake them out right down to the brickwork (or lathes) leaving a gap in the plaster of about 5-10mm.
Any really loose plaster should be removed too but don't pull it off as that will loosen more plaster. Use a light chisel, knife or sharp screwdriver and cut the plaster off.
Remove the dust and wash the crack out.
Then fill the gap completely using an appropriate filler (polyfilla is quite good in this situation as it has good adhesion with some flexibility with strength) and sand it down.
Then decorate in the normal way.
I have found this method normally lasts for some time and is able to resist minor movement.

If the cracks are greater than 5mm it is sensible to remove the plaster directly over the crack and attempt to insert some mortar between the bricks to stabilise the fault. It may be necessary to remove some original mortar to get the new mortar in place.

 

[GSJ]

Most older houses built on clay have old cracks.

Many people make the mistake of just plastering over the cracks only to find that they usually reappear shortly after...

If the patch plaster is too thin it has no strength and cracks easily.

Thanks Lime,

Your post makes a lot of sense and is very reassuring for me!

I have just been assuming that there is going to be continual and substantial movement, but as you say, this may not be the case. I need to monitor this, as I only purchased the property recently.

I think the cracks currently present were patched up in a very simple way by the previous owners when I had bought the property (looking back at photos I took initially, I can actually see the faint outline of where the cracks were painted over!), and thus a few months later they have just re-opened!

A proper crack repair along with the use of a flexible sealant may just do the trick and save a lot of expense and heartache!

Thanks for that wisdom!

GSJ

 

[Penners]

I'm afraid I agree with Lime. If the building is moving regularly by substantial amounts, I think you could fill your cracks with whatever you liked from now until doomsday, and they would still reappear sooner or later. If you're planning to sell the property, then I don't think you have any option but to fill them as best you can, and then hope they hold until the deal is done! (What you tell the purchaser is entirely a matter between you and your conscience).

I have no experience of the crack stitching technique that has been suggested, but frankly I don't believe that would work either. I think you'd just get cracks around the stitched sections. And wallpaper would just wrinkle, as Lime says.

 

[GSJ]

Thanks Penners,

I think the key issue here for me is exactly how substantial further movement is going to be. My feeling (and my hope!) is that it is not going to be that great. From speaking to the neighbours, they have cracks in their properties that have been there for sometime, and that they say are not getting worse. Although the property is on reactive clay soil, I don´t believe it to be ´unstable´in nature (just my opinion/hope though, while awating a geotech. engineers review!).

I agree with the comments about the wallpaper, the wrinkling/ripple effect is not going to look good, plus, if it tears then you might have to replace the whole thing.

With respect to cosmetic solutions in the context of further substantial movement, the only other option I am aware of is the use of new plasterboard sheeting on top of ´gypliners´(or resilient wall mounts plus furring channels), to create a non-load bearing/´floating´wall.

Anyone have any experience with this?

GSJ

 

[Moo]

What is 'reactive clay'?

 

[Penners]

GSJ - sorry, no. I have no experience or knowledge of any of those products or systems.

But - like Moo - I'd be interested to know what "reactive" clay is.

 

[biffvernon]

What is 'reactive clay'?

I think, in this particular context, it means a clay that swells and shrinks quite a lot as it gets wet and dries. It give rise (or sink) to the sort of conditions in which subsidence can occur.

 

[Moo]

You mean, like good old Thames Valley mud?

 

[Penners]

Or (worse news for us, Moo) East Anglian clay.

 

[GSJ]

biffvernon, yes that is what I basically understand to be reactive clay soil.

Thames Valley mud, East Anglian clay? Don´t know about these.

GSJ