Covering up cracks in internal walls

Hi all,

A friend of mine has a single-fronted, semi-detached, Victorian-era period home (c1900), in the inner northern suburbs of Melbourne.

Due to a number of factors (reactive soil in the area, large trees on neighbouring properties etc...) there are cracks through several of the internal walls (and external walls too), up to 1cm wide in some areas.

A recent Archicentre building inspection has noted these cracks to be quite significant, but common amongst properties in the area and of this age. Essentially, the house is not expected to fall down, but fixing the cracks permanently is very unlikely. Restumping, underpinning etc...may still not prevent further cracking.

My friend has done some basic things like removing a large tree in the rear yard close to the rear and side wall, and improving subfloor ventilation, as simple ways of helping to reduce the problem of cracking. They are considering a new damp-proof course, but this appears quite expensive, and as it is an investment property, she is not keen to do this at present.

The property is rented out at present.

The question here is -

What can be done to cover up the cracks, cosmetically?

ie, given that permanently fixing the cracks is unlikely, what can be done to improve the cosmetic appearance of the walls?

1. The simplest thing, I presume, is filling the cracks with plaster and repainting...but with a change in climate and further movement, they will obviously just re-open.

2. Another option, using a fibreglass or paper plaster tape to cover the cracks, then repainting. I am not sure how lasting this method would be? Will it last longer?

3. Another option, using plywood or pine-panelling as the internal wall cladding, would these materials be less likely to crack?

I am looking for the simplest and most lasting solution to this problem of cracks. Mainly a superficial, cosmetic solution, so that when my friends property is re-valued by the bank, or is for sale, or open for new tenants, it looks good on the outside...

Any thoughts or ideas would be much appreciated...

GSJ

We have a section in our web site on repairing lathen plaster.

The repairs if done properly will last provided no further movement occurs.

You have no control over that. Over time there will be new cracking but that is the same for most buildings.

No one put more effort than me into crack prevention in my new home. But 5 years in and some minor cracking has occured in stress areas. I will wait another year or 2, then repair them.

Any superficial repairs will definitly crack again, the crack has to be dug out and filled properly.

The plywood is not a very good option it will look like ****T

Lining boards will work if you like the timber look but expensive and way too much timber, and would not suit the era.

Another option wich is also expensive but the best option for long term, is to rip out all the lathen plaster and replace with plasterboard. This is a major renovation though!


Cheers Rod Dyson

Thanks Rod,

Is it not possible to just put a new plasterboard on top of the existing wall, hence covering the cracks, instead of removing the lathen plaster first?

Also, the plywood, can´t you paint the plywood?

GSJ

I agree with rod.Ply will look like painted ply,not like plaster.Is it a timber house or brick?

Tools

You can put plasterboard over the lathen plaster. In fact its a good idea where you can, as it will add to the insulating and soud proofing qualities of the home.

However if you are going to do this you should remove and replace all skirting architaraves and cornice. Here you are getting into major renovation work.

We have in the past, (at the owners insistance) put plasterboad straight over the lathern plaster WITHOUT removing arc's skirtings,etc. The problem is how to finish off where the plasterboard butts against dissimilar surfaces. Casing bead looks terrible, stopping up will crack, and stopping angle makes the job expensive and will also hairline crack eventually.

Not to mention you will lose all definition in the edges of skirting, cornices, etc. I really is not a good look.

As metioned above, ply will look like ply. YUCK!!!!

If you can't afford to strip out and replace the plasterboard profesionaly, then don't do it at all. It won't help the value of the place if its not done right!

Do the next best thing. Patch the cracks properly as shown on our web site. We also show what is "patchable" and what is not and how to do it.

Cheers.

Thanks,

What a great forum...just like somersoft.com.

It is a brick house.

Rod, it sounds like the best option is the plasterboard sheeting, and if doing it properly and removing architraves etc...then it will be costly...do you know very rough ball park figure for say a 2 bed house with floor area 100m2??? I have no idea what sort of numbers we are talking here?!

Of note, the hallway is the only area of the house where there is virtually no cracking, and I believe there may be plasterboard sheeting here from the architect´s comments.

Otherwise, filling cracks properly would be my other option...

Is "flexible sealant" something that could be used here, since there has been and may continue to be some movement in the house???

Regards,

GSJ

No! Flexible sealant will fix the cracks, yes, but you won't be able to "hide" the cracks with flexible sealant.

It can't be sanded, and it shrinks, etc.

I have no idea what the cost of replacing the architraves etc. would be. The cost of plastering would depend on the type of cornice etc.

It is the sort of job you would need to carefully cost out before starting, so there are no hidden surprises. You would need to factor in electical costs etc. as well.

Where in Melbourne is the house? I may be able to call in over the next week or so and give you an idea which is the better option. We only contract out on new housing and units etc. So I would NOT be able to do the work. But I would be happy to give you an estimate of what you would expect to pay a reasonable contractor for the plastering only.

Cheers

Rod

Thanks Rod,

The house is in Northcote.

I am overseas at present. Will try and contact you on my return.

Will do more investigations re. costing in the meantime.

This thread has been very helpful for me.

GSJ

GSJ Northcote is good email me when you get back.

HJO, render works well. The only probelm with it is that, most people find it hard to work with. and even harder to get a quality finish.

Digging the crack right out back to the substrate is the most important thing with fixing cracks. When you have done that what you fill it with is not that important. Some products give a better result than others astheticly and are easier to use for various reasons.

Cheers

Rod

If you get a quote to cover the walls with plasterboard then you'll also need to get a quote form a carpenter to remove all the skirting and architraves and to refit them. The problem you'll encounter though, is that the walls will be 2 x 10mm thicker, thus the jambs will be 20mm too narrow and the hingepoint of the doors will be back behind the plasterboard. The doors will need to be removed and rehung on the extended jamb and the hinge and lock mortices will need to be patched and recut. More work, more money....:(

Mick

If you are going to take the render option (which is the cheapest and in keeping with the house),make sure you fix some expanded metal over the cracks and fix them to the brickwork on each side.Even a heavy chicken wire will do.Then render and set over the top.

Tools

Ive got some issues similar to you with plaster which is lathen in a couple of rooms in my house. I'll take some photos soon and post them. I took away the wallpaper an in the corners of the rooms there is like a strip running from the roof to the skirting board joinging the plaster (i think). I have no idea what it is but it looks crap!

I just got my house restumped and the cracking is not as bad as expected which is good. I'm hoping to not have to replaster because of the cost (the extension is costing enough!) so Im hoping tp patch it up uf I can figure out what to do with the corner strips.

Good luck with your efforts repairing the plaster and let us know how you go.

hello,

if cracks <2mm i would you use a good quality sealant like Sikaflex (around $17 at bunnies)

even up to 20mm (2cm) this stuff can be used it is a very high quality polyurethane sealant

keep flush with wall, any excess can be sanded, but you dont want to sand your finished sealant, ie, sand of any excess on sides of crack

when painting over it needs to be done in two distinct coats with 12hrs drying time between coats

is best overcoated with textured paints or suede effects paint, something with a bit of hiding power and flex.

I believe this would be the most cost effective way

have rectified numerous render jobs this way

the sikaflex will allow for movement to occur and most arylic paints have a little bit of give to them

apart from that, I would think rendering would be the next best thing

if substrate is reasonably sound, but cracks would still need sealant and mesh appiled in wet render over the top or expanded metal as mentioned

thankyou
myla

Looking at this photo from an old posting maybe I dont have lathen plaster?

http://www.woodworkforums.ubeaut.com...7&d=1098868722

Part of the plaster has detached itself from the skirting board at the bottom. When I push the electrical plug in the powerpoint I can push the plaster in. Judging by this photo it wouldnt be possible?

How can I tell easily whether its lathen or not???

Quote:

---

Originally Posted by myla

is best overcoated with textured paints or suede effects paint, something with a bit of hiding power and flex.

---

That is because you can't get a high quality finish with sealants.

The line of the crack will always show up unless texture finished over.

Everything you do will work to some degree or another.

What you end up with will definitly be determined by your skill level or how much you are prepared to pay.

Cobber you have got lathen plaster there.

Cheers

Rod

Rod - if its lathen plaster do you have any idea what to do with the corner sstrips that I have in a few of my rooms....they look awful. I'm inclined not to replaster as the condition is not too bad apart from the corner strips? I could maybe sand the strips or replace them. I'll take a photo on the weekend as i appreciate its a but hard to comment without a photo.

By the way whats makes you think its lathen plaster?

Lathen plaster is sand and cement render over wooden slats, with a skim coat of hard plaster over it.

The photo shows the slats.

Post a photo so I can get an idea of what you have got.

Cheers

Hi,

Here´s a picture of the cracks across the right side wall at the back of the house, where the living and kitchen area is. I think this area of the house was renovated many years ago by a previous owner. Makes me cringe whenever I see it...Any thoughts...

GSJ

http://images1.snapfish.com/3478657%...A829%3A8nu0mrj

They can be dug out and repaired

Looks like a bit of work. I have cracks going all around the room in one line also. I will post my photo next week if i remember. If you can fix that then it gives me some hope.

I pulled off one of the corner strip bits and its definetely lathen plaster as there is 2 pieces of wood strips behind it and thick threads.

I am not convinced that the rest of the plaster is lathen though. Half of the house has been demolished I can see the plaster from the back of the exposed house....if it was lathen surely I would see all the strips. All I can see us a white lumpy sheet. The plaster has alot of threads hanging out of it not as thick as the ones from the lathen strip I pulled off.

Was there a plaster after lathen and before the modern plasterboard by any chance Rod?

Thanks

Cobber

Yes fibrous plaster sheet replaced the use of lathen plaster.

Then came plasterboard.

Fibrous plaster sheet typically was made in 2.1 m wide sheets so the join would be at door height and covered by the picture rail. It is a common practice when renovating to remove the picture rails and stop up the join.

We see it often where the stopping hasn't been done well in older renovations and the join cracks. Another problem is the sheet below the picture rail is often thicker than the sheet above giving you and uneven finish.

Cheers Cobber.

Ah I reckon thats what I have then as there is a gap between or underneath the picture rails. That makes sense then. Fibrous plaster sheet with the horrible corner join strips.

Rod is it easy to fix cracks in fibrous plaster (as per lath plaster). I havent seen much on this website. Is it the same technique as your normal plaster sheets or lathe plaster as described in your website?

Thanks for your help.

Cobber

Treat cracks in the joins of fibrous plaster much the same way as you would a cracked join in plasterboard.

The only thing is the join in fibrous plaster is not rebated, so you can assume any previous attempt to fill them will cause a "lump" like a butt joint in plasterboard.

When fibrous plaster was jointed there was no tape the used to face scrim with hemp. So one way to get back to a reasonable flat surface it to get into it with some heavy duty sand paper and a belt sander. (just along the join and only if you really need to). If you hit fibre STOP. you cant sand any more. If you break through the to the fiber the sand paper will cause the fibres to raise up and it is very hard to coat over them.

If this happens, I have found scorching them is the best way to get rid of them. Take care don't burn the place down!

You will find a thread here on fixing cracks in plasterboard joins.

Cheers

Rod Dyson

Thanks alot Rod. When I get around to doing it I am sure I will be asking questions. In anycase I'll post some photos at some stage soon.

cheers

Cobber

I don't think we are talking about lathe and plaster at all. If these houses are brick it may apply to the ceiling but the walls sound like solid plaster. Much the same job with a weak but thick base layer and a harder top coat. Look at what Tools said about bridging the gap, there is a product made for the job or bird wire can be used. Get someone in to have a look first, your jumping the gun talking about plastering over etc, when what it may need is a proper repair job. A straight repair will be a lot less fiddly, but may not solve the problem. Ground moisture, drainage etc may be causing a lot of the problem. Large trees, heavy clay soils or just a few very dry years could all be part of the problem.

I think everyone needs to take a deep breath some of the ideas such as sikaflex and plastering over may not produce a very appealing outcome.

John

I would still go with cutting out the cracks to the substate be it bricks or laths and fill them with cornice adhesive with top coat over.

The most important thing is to open the crack wide enough to get the material used to repair right in to the substate.

Using chicken wire or expanded metal, then rendering over is not required in most cases, of cracking in solid plaster or lathen plaster. Definitly not required for simple cracks but is useful if a larger area needs to be rendered, but even then a combination of cornice adhesive and perlite will adhere perfectly. We even make cornices institu, around curved walls to get a seamless finish, with this mix.

Chicken wire or expanded metal is essential if you are rendering over a non porous surface, where the render cannot bond. Eg, painted walls or glazed bricks etc.

Obviously if the cause of the cracking in the first place is not addressed, the most likely result is further cracking.

We did a major renovation of the historical society in melbourne that had very seveer cracking in the solid plaster walls.

They wanted the restoration to be original, as it was on of the oldest buildings in Melbourne and was where Burke and Wills left on their historical journey.

We had to reconstruct 1 meter wide cornices etc that had basically fallen apart.

The buliding had some under pinning done to stop the sinking at the junction of an old renovation. Once this was done we placed plastic tabs on the cracks with markers to see if over a period of time the cracking worsened. When satisfied that the building was secure we cut out all the cracks, removed loose and drummy plaster, repaired them all in the exact manner describe on our web side. For a fantastic result.

Needless to say the reason for the cracking in the first place should be investigated and the building made stable.

In most cases cracking repairs are done after reblocking etc.

Just a quick question, might be an obvious answer, but...why is plasterboard sheeting less likely to crack? Is it much more flexible, rather than "brittle", like other materials?

If I were to do this to the Victorian-era property mentioned at the start of this thread...would the plasterboard sheeting not just crack with further movement????

GSJ

G'Day GSJ,

I'm thinking I've missed something.
Is the present cracking in BRICKWORK or
Rendered Plaster?

I'm thinking EPOXY Injection,
BUT
that would only transfer the cracking to somewhere else.

NEXT DOOR ?????? :D :D

hello,

cracking looks like through solid plaster to me and sure if drummy would need to be replaced

this is why a flexible sealant is an immediate fix, as provides continual movement if the "larger issues" are not resolved

as stated need seude effects or textured paint or around 4 coats of quality paint to cover and make presentable

I think GSJ's brief was for a cost affective "fix" and from memory is currently rented and therefore addressed with minimal fuss

thankyou
myla

Ivan in OZ

The cracking is on the plaster I think, cannot see the bricks on the inside, but on the outside walls there is cracking seen on the bricks...what is EPOXY injection?

GSJ

hello,

you have solid brick walls

they then render (sand & cement) to level and then apply a hard set plaster (smooth finish)

the cracks are through the hard plaster and render, and generally due to movement of the brickwall which has moved because of foundation issues etc

most likely the cracks would be over/around the mortar lines of the brickwork as this is the weakest part of masonry wall

if cracks are through bricks you are more likely to get reasonably straight vertical cracks

thankyou
myla

Thanks myla the lingo you all use makes sense now.

Yes, on the external walls, the cracks seen are through mortar lines

GSJ

Hi,

Having just re-read this thread the two options which stand out for me are:

1. New plasterboard sheeting over the top (with removal/replacement of architraves/cornices/skirtings etc., and repainting).

This is a part of a major renovation though and costly.

2. Flexible sealant.

Allows for movement and much cheaper.

I am inclined to initially use flexible sealant (as a cosmetic solution, eg, to present to new tenants) as I am not convinced yet that the movement issues can be resolved.

The property is on reactive clay soil. Although work is planned for this property to fix other potential causes of movement, fixing these may simply minimise movement and not eliminate it all together (cracks will need monitoring over a period of time to assess this ?12-18months). Thus any crack repair, even if done well, may still crack again.

The only thing that remains if this option is taken is,...what will it look like???

It is an old house, it has character, and many imperfections too...so I would not expect it too look that great, just acceptable and less frightening than having huge cracks through your living area or bedroom wall.

Does anyone have any photos of what a crack filled with flexible sealant and then painted over looks like??? myla?, before/after shots?

Any other comments appreciated.

Cheers,

GSJ

hello gsj

will see what I can dig up as do not have digi camera

the cracks will probably need some sanding as may of moved out as well as open

need flat or low sheen paint and several coats or seude affects etc

everything needs to be allowed to dry correctly ie. seal one day, paint 1st coat the next etc

thankyou
myla

Thanks Myla, any photos would be good.

I just read in a previous thread regarding expansion joints.

Is there a role for expansion joints (or I think also called ´articulation joints or control joints´ in the cracks seen in the photo shown previously? Can they be painted over, and how would they look?

Could someone explain what these are and when/where they are used?

Thanks,

GSJ

Expansion joints will look ugly in that application.
Expansion joints are normaly used in stair wells between floors of buildings. Or in commercial projects where there are long coridoor ceilings or walls. Usually installed at critical points in the building adjacent to other structual expansion joints.

The flexible sealant option can surley only be seen as a very temporary solution. I cant say I have ever seen this done where the cracks are not visible afterwards, I have seen many attempts that have gone horribly wrong.

Here is a crack repaired with sealant that has shrunk back. Also a typical expansion joint use.


Attachment 29134Attachment 29135

Cheers
Rod

Quote:

---

Originally Posted by rod@plasterbrok

Here is a crack repaired with sealant that has shrunk back. Also a typical expansion joint use.


Attachment 29134Attachment 29135

Cheers
Rod

---

Hi Rod,

Thanks for all your replies on the various threads to vother members thread (including mine;)). Saying that how would you (as an expert in this field) go about correcting the crack in the picture you uploaded?.

The reason I ask is that I have several cracks starting from the corners over the door (as shown). It would be nice to get it fixed on the first attempt rather than run into the problems other have encoutered here previously.

Kindest regards
David

With this type of crack, which is in plasterboard, I would use wet and stick paper tape as described in another thread here, on fixing cracks in ceiling joins.

There is no need to dig out a crack in plasterboard as descibed, for cracks in render or lathen plaster.

Cheers

Rod

Rod, thanks for the clarification re. expansion joints.

The photo there of the crack repaired with sealant looks quite bad, certainly not the cosmetic outcome I am looking or.

I hope Myla or others can dig up some photos to show a better outcome than this.

If not, I may have to initially just do a good crack repair as you suggested Rod, and also attempt to fix potential causes of movement and thus minimise future movement and repeated cracking.

GSJ

I read another thread in the forum where someone was attaching plasterboard sheeting to something called &#180;furring channels&#180;, effectively creating a wall that moves with any future movement in foundations...see the quote below -

&#180;therefore intend sealing wall sheets to furring channel (allowing sheets to move up and down on walls) and also sealing wall sheets to floor...&#180;

Anyone have any comments re. this, I presume it would be an expensive process.

GSJ