I am concerned about the crack that has been growing where an addition was built onto the house many years ago. Just looking for some possible reasons for it and advice as to who I should get in to take a look at it.
I would suggest this is something that needs to be assessed by a qualified structural engineer. I'd hazard a guess that the addition has subsided because an insufficient size or quantity of piers has been used in the construction, or significant ground subsidence has occurred over time. However, providing a reason behind the issue is best left to the professionals.
Subsidence was the problem due to poor drainage and I have had a structural engineer in and underpinning completed. Now I would like to have a go at repairing the crack. I’ve cleaned it out and am wondering if it’s best to fill the crack with mortar as it’s so wide ... or can I use expanding foam?
It's good to know that you've identified the problem and solutions have been implemented.
To repair the crack in your plasterboard wall, I suggest using Gyprock CSR 2.25kg Less Mess Multi-Purpose Joint Compound. It is pre-mixed and ready to go. You will also need a Builders Edge 100mm Plastic Joint Knife if you plan on having a sharp edge finish to your wall. My handy advice for this project is to not rush filling the gap. Give the plaster time to dry and slowly build up to cover the gap. This will avoid long drying times and plaster sag.
To repair your outside wall I recommend using the Dingo 10kg Mortar Mix. This is a sand and cement mix and can be easily pushed into the gaps. Remember to give the area a good clean with a brush to remove any loose cement that may still be attached.
Here is a handy step-by-step guide: How to repair cracks in plaster
Let me tag our experienced member @TedBear for more advice.
We look forward to seeing your walls repaired.
Thanks for the advice Eric. I had already purchased the Dingo Mortar Mix so was on the right track there! (Phew!). As for the internal, the crack is so deep, I have filled some of the large spaces with expanding foam and cut it back to about 1cm below the edge of the crack to plaster over. I am hoping that will work. I will definitely go slowly for both internal and external walls. I did read that I should wet down the external area as the brick will soak the moisture out of the mortar.
Hello @JumBuck (Katherine)
I'm glad I could help. Using the expanding foam is a smart idea. If you happen to put in too much just remember that it is a soft expanding foam and you can trim it off with just a flat head screwdriver. Would it be possible for you to post updates while you repair it? I'm sure our members would like to see the process while it's being done.
We look forward to seeing your updates.