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How to repair wall sheeting joints in an old house to prevent re-cracking?

QLD-Lois

Hi,

We live in an older QLD worker's cottage. The walls in the lounge/dining/bedrooms are clad in a mixture of masonite (inside most exterior walls) and fibre cement sheeting (newer internal partions). In the past we have taped and filled the joints between sheets for a smooth painted finish, but within a year or two the cracks are back with the changes in temperature.

Since one bedroom was a real patchwork of joins, we've recently stripped it out entirely and had it re-clad in gyprock, but it was such an undertaking that I'm keen to explore other options before having to go down the same path with other rooms.

Dunlop FC Jointing Compound has been recommended, but I've read that it sets like stone and is very difficult to sand down. I've also looked at James Hardie Top Coat, but it reads like waterproofing is its main purpose which is not what we need.

I would love any suggestions and recommendations on products and method that will achieve a smooth finish wall that will resist cracking through changes in temperature.

Thanks so much!!

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EricL

Hello @QLD-Lois

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your wall sheeting joints.

Have you considered covering the joints with https://www.bunnings.com.au/31-x-11mm-5-4m-white-moulding-pine-fj-primed-dar_p0020885 as a wall feature. It may seem a bit old fashioned, but it will cover the joints of the sheets, and you'll never see the split in the joints again. Another option is to drill more screws into the sheet, specifically as close to the joints as possible. This will reduce movement but not totally eliminate the shrinking of the sheet. You can then apply the tape and filler on the surface.

In the interest of health and safety I suggest having your walls tested for asbestos before you begin sanding, just to be on the safe side. If the test is positive, I suggest engaging the services of an asbestos removal specialist. If the test is negative, you can continue with your repair plans.

Let me call on our experienced members @Dave-1, @Nailbag and @Noyade for their recommendations.

If you need further assistance, please let us know.

Eric

Dave-1

Good Evening @QLD-Lois

Its a hard call to decide on redo a wall or a room. I would be tempted to redo the rooms one at a time as you move through renovating it as it will give the best long term solution. Thats not a cheap call to make tho its my first choice.

I also though of a timber strip over the join points to help cover the cracks/joins. I like older houses and that style would suit a queenslander for sure. Second choice

The last thought that popped into my head was a hard straight edge, as in a metal edge strip (like the ones you use on plaster corners or even the wrap around edge for plaster) To define and give a clear section for movement. I am think liek a breakaway expansion joint something that you do to make sure that area will have the ability to flex. It could be hidden behind portrait style pictures, the timber cover strip but its more of a design feature to marry the two dis-similar products together.

Dave

Nailbag

Hi @QLD-Lois

A couple of decades ago I lived in Maroochydore in an old government house. All the wall and ceilings were cement sheet of some type and a Super 66 Asbestos roof. During the renovation, I had given up trying to seal sheet gaps like yourself. Instead used cover trims which had a low 2.5mm profile and tapered sided. Once painted the wall colour, though obviously noticeable, it was neat and the ugly gaps were gone for good.

Nailbag

MitchellMc

I'd agree with the others @QLD-Lois. I have a similar issue in my home. I patched the same joint line several times, only for it to reappear a year or so later. Since using a https://www.bunnings.com.au/30-x-5mm-2-4m-tasmanian-oak-round-edging_p0083866 I haven't had to deal with the crack again.

Mitchell

QLD-Lois

Thank you everyone! I really appreciate you all chipping in with your thoughts and expertise so quickly!

I wasn't too keen on the idea of a timber trim over the joints - mainly because of the aesthetics, but also because we have high ceilings (3150) so in some places there are horizontal cracks as well as vertical. I am tempted to strip out and replace the wall cladding one room at a time but, after our experience with the first room, I think the only realistic and efficient option would be to get the professionals involved and gut half the house which is a bit beyond us at the moment.

We're going to look at https://www.bunnings.com.au/specrite-2700-x-600-x-21mm-hevea-batten-acoustic-panel_p0661031 which should take care of one wall. If we go for an interim tidy up on the others until we can consider a more thorough rebuild, would Builders Edge 50mm x 90m Alkali Resistant Render Fibre Cement Tape and James Hardie 3kg Compound Top Coat Tub be the best products to choose?

Thanks again,

Lois

MitchellMc

Potentially, that could work @QLD-Lois, but traditional Hardieflex sheets were never set on the joints. The method you are describing works well on Wet-area Villaboard sheets that have a rebated edge, where the tape and filler sit within it. Using it on a sheet that doesn't have a rebated edge would mean you'd need to taper it out onto the wall like you would be setting plasterboard sheets. Your cement sheets are painted, so how well the top coat will adhere to the surface is questionable.

As a test, why don't you try filling the gap with https://www.bunnings.com.au/selleys-480g-white-3-in-1-silicone-sealant_p1230061 which is a flexible and paintable gap filler. That would resist movement more than a cement-based filler. I'd suggest sanding the crack to remove any paint that might have lifted and is proud of the surrounding wall. Apply the filler and immediately remove the excess with a scraper. Start at the top of the crack with the blade against it and the handle facing down and drag the scraper down the crack, which helps push the filler in and screed it so it's flush with the surface. You don't want any proud of the wall as you can't sand it afterwards.

Since I've mentioned sanding here, I'm going to reiterate the Asbestos warning above. It's imperative that you know what you are working with before sanding or disturbing a cement sheet of that age.

You can then prime the area and paint. This could give you a reasonable enough finish to buy some time as you replace the sheeting.

Mitchell

QLD-Lois

Thank you Mitchell. I'll have a look at a small test area and see how well this method works out for us.

We have done some asbestos removal already and will be sure to take all the necessary precautions. In the room we've already worked on, we found that the inside of the external house walls were just masonite. Fibre cement sheeting was attached over VJs on internal walls and had massive "Asbestos Free" stamps all over them on the unpainted side. We'll be sure to check what we're dealing with before starting any work in the next room/s.

Thanks,

Lois

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