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Garage breeze blocks - how to make it waterproof and insulated as an indoor storage room on a budget

Anonymous user 09/03/2024 - 3.17 PM

Hi, I have an external garage detached from my house. The walls are made up of breeze blocks, however it wasn't done very well and you can see tiny holes where water could easily slide through. My goal is to ensure no water can come in through the outside, and somewhat insulated in the inside so that it can be plastered and used as a storage room, most importantly I don't want any damp appearing! My understand is that the outside side of the breeze blocks need to have a 2 coat render to ensure water cannot enter the walls. As for the inside, I am familiar with two options: 1) Batten and board the walls using 22mm polystyrene plasterboard, then plastering the walls 2) Cover walls in moisture resistant vapour barrier, then batten the walls and fit 100mm cavity insulation, followed by 12.5mm plaster board, then plastering the walls I feel option one should be enough insulation for a room that won't be used often. However, option two has a "moisture resistant vapour barrier" which sounds like extra layer of protection to protect damp. I'm also concerned that option 2 will be more expensive. My question is, is it possible to go with option 1, but with the moisture resistant vapour barrier applied on the walls before I apply 22mm polystyrene plasterboard? Otherwise, if you have any other budget suggestions, I am all ears. Thank you! Edit: Thank you to the person who replied and suggested option two. I noticed you said it wouldn’t be much of an extra cost, in terms of per square metre, how much are we roughly talking? E.g. extra £5 psm etc.