Hi, need a bit of advice, please can any painters help with this ?
I have a large new build timber double garage built on top of dwarf blockwork walls, the walls are constructed from smooth paint grade concrete blocks 5 courses high (approx 750mm high), the walls also act as retaining walls as the whole garage is built into sloping ground therefore externally the walls are below ground level and not visable at the rear.
During construction the outside faces of the walls were fully sealed with bitumen primer paint and a proper tanking membrane was applied prior to backfilling of the soil around both the side walls and the rear wall of the garage, this was done to prevent dampness passing through onto the inside of the walls which are fully visable inside the garage.
I would now like to paint the interior side of these concrete block walls on the inside of the garage where they are visable with white paint and would like to ask how best to go about this, the issue being that there is still some slight dampness in the walls despite all proper tanking done externally, I want to seal the inside of the walls to prevent any dampness inside the garage.
There are a number of options I can see:
1) Use a white damp blocking paint as a primer on the bare brickwork (how many coats?, should I thin down the first coat?, can these type of paints be painted over with either regular water based or oil based masonry paint afterwards?).
2) Use only oil based masonry paint (how many coats?, should I thin down the first coat? would this type of paint prevent any dampness showing through?).
3) Use a water based masonry paint (if dampness remains and shows through, can this then be painted over with the white damp blocking paint or can damp blocking paint only be used on the bare brickwork prior to painting?).
It's all very confusing to me so any advice greatfully recieved.
Thanks guys for your patience and understanding.
Are you a tradesperson and able to answer this question?
Initial recommendations as follows :
▪️The correct diagnoses must be established before undertaking any correctional works you have mentioned. I would have a number of questions, it's a bit of an investigation process really.
> Use a damp meter to measure moisture level and to confirm if it is (most likely) penetrating or rising damp. And take moisture level readings at different points along the wall.
> High or varying moisture levels could indicate that the exterior damp proofing as failed in some way (therfore check is it under guarantee?) or if reading moderately low (reading could be higher lower down) it could be that the wall is still drying out, which can take a long time because every application is different.
> High quality waterproof paint system (that I would be happy to recommend) if applied correctly are effective however this comes with a caveat, which is basically that if you don't follow the above advise you could move the water ingress to another part of the building resulting in further damage to the fabric of that building. I have seen this first hand where the walls in a utility room were sealed with damp proofing paint and the adjacent wall into the kitchen was effected resulting in damage to the kitchen units behind which was hidden and resulted in new units being needed.
If I can be of any further assistance please contact me.
Simon Best
Paragon Property Services
Painting over damp brickwork can be a bit tricky, but it's essential to address the dampness issue before proceeding with any paint. Here are some steps and options you can consider to paint over damp brickwork in your garage:
**Step 1: Address the Dampness Issue**
Before painting, it's crucial to ensure that the dampness problem is adequately addressed. Dampness can affect the paint's adhesion and cause it to peel or blister over time. Here are some steps to address dampness:
1. **Identify the Source:** Determine the source of the dampness. Ensure that there are no ongoing water leaks or drainage issues that could be causing the problem.
2. **Ventilation:** Ensure that the garage is adequately ventilated to allow moisture to escape. Proper ventilation can help reduce dampness over time.
3. **Dehumidifier:** Consider using a dehumidifier in the garage to reduce moisture levels. This can be especially helpful if the garage is in a consistently damp environment.
4. **Damp-Proofing Paint:** Consider using a damp-proofing paint or sealer specifically designed to block moisture. Apply this to the damp areas according to the manufacturer's instructions. It's essential to allow this product to cure properly before painting over it.
**Step 2: Choosing the Right Paint**
Once you've addressed the dampness issue, you can choose the appropriate paint for your garage walls. Here are the options you mentioned:
**1) White Damp-Blocking Paint:**
- Apply a high-quality white damp-blocking paint as a primer on the bare brickwork.
- Follow the manufacturer's recommendations regarding the number of coats and any thinning requirements.
- Some damp-blocking paints are compatible with both water-based and oil-based masonry paints. Check the product's instructions or consult with the manufacturer to confirm compatibility.
- Once the damp-blocking paint has properly cured, you can proceed with your chosen masonry paint.
**2) Oil-Based Masonry Paint:**
- If you decide to use only oil-based masonry paint, ensure that the dampness issue has been adequately addressed before application.
- Apply multiple coats of oil-based masonry paint as per the manufacturer's instructions. You may not need to thin down the first coat.
- While oil-based paints can provide good moisture resistance, they might not be as effective at blocking dampness as dedicated damp-blocking products.
**3) Water-Based Masonry Paint:**
- You can use water-based masonry paint, especially if you prefer an easier cleanup and fewer fumes.
- If dampness continues to be a problem and shows through the paint, you can consider applying a white damp-blocking paint over the water-based masonry paint as an additional barrier.
**Important Tips:**
- Ensure the walls are clean and dry before applying any paint.
- Follow the specific manufacturer's instructions for each product you use.
- Use high-quality paints and tools for the best results and durability.
- Allow sufficient drying and curing time between coats and before using the garage.
Ultimately, the choice between these options will depend on the severity of the dampness issue and your personal preferences. Always prioritize addressing the dampness problem first to ensure the longevity and effectiveness of your paint job.
Answered10 September 2023
1
Anonymous user
Hi There, To paint the interior side of concrete block walls in a garage that has some slight dampness, there are a few options:
1-Use a white damp damp-blocking paint as a primer on the bare brickwork. Apply as many coats as necessary to cover the surface, and follow the manufacturer's instructions. It is not necessary to thin down the first coat. Once the primer is dry, regular water-based or oil-based masonry paint can be applied on top of it.
2- Use only oil-based masonry paint. Apply as many coats as necessary to cover the surface, and follow the manufacturer's instructions. It is not necessary to thin down the first coat. Oil-based masonry paint can help prevent dampness from showing through.
3- Use a water-based masonry paint. If dampness remains and shows through, it is possible to paint over it with white damp blocking paint. Apply as many coats as necessary to cover the surface, and follow the manufacturer's instructions. It is not necessary to thin down the first coat.
It is important to note that the walls should be fully dry before painting. If there is still some slight dampness in the walls, it may be necessary to wait until they are completely dry before painting. Additionally, it is recommended to remove any loose or blistered existing paints before applying a bituminous paint.good luck
