Can I screed over bitumen?
because a latex based screed should never ever be used over Bitumen, the green colouring may be due to a chemical reaction between the two substrates which will require the screed to be mechanically removed.
Can I screed over DPM?
I would lay the DPM straight onto the existing and screed over. Insulation would be a good idea, but it also may not be a bad idea to knock the whole thing down and start again if the walls are only 4″, the floor is rough, and the roof probably leaks too.
Do you need to prime before screeding?
Priming Liquid Screed Floors (Anhydrite)
Primer is absolutely necessary if you have an anhydrite screed (aka calcium sulphate). … If you do, there will be a chemical reaction between the screed and the adhesive, and the adhesive will eventually separate from the screed.
Can you screed over painted concrete?
Firstly no you cannot use any type of screed over a painted subfloor, the paint must be removed either by using a buffer with an abrasive pad, or scarifier. Secondly you will need to use a screed that is recommended for outdoor use.
Will SBR stick to bitumen?
From reading previous threads, Professional tilers on here and admin have firmly stated that a good rub down with a degreaser and a neat coating of Bal SBR bond is fine over the bitumen before tiling commences.
Do you need a membrane under screed?
A membrane of 1000 gauge or thicker should be laid immediately under the pipework (above the insulation board) as a slip layer, and to prevent leakage of the screed before setting.
Can you screed over damp proof membrane?
The current recommendations for an effective damp proof membrane are that the ground should be constructed using screed with the damp proof membrane laid either on top or below that layer. … This should be laid on a bedding material such as screed which doesn’t damage the sheet and has fully sealed joints.
Do I need a DPM under screed?
Trapped residual moisture within the concrete or screed is drawn to the surface, which can result in hydrostatic pressure forcing up the finish. If there isn’t a DPM then this will show itself as unpleasant blistering across the floor area.
Does screed need sanding?
Sanding is required to remove surface laitance and absorb primer. Early sanding of your floor will improve drying times by removing the laitance allowing moisture to escape quicker. Sanding should be carried out using an orbital sanding machine with integrated vacuum.
Does screed make a mess?
Cons of Sand/Cement Floor Screeds
Sand/cement mixes can result in a patchy quality, uneven finish and a propensity to develop cracks. Where floors are uneven, a self-levelling compound may need to be applied before floor tiling.
What is self Levelling screed?
Self Levelling Floor Screed is an essential component used to form a level surface upon which you can apply tiles, natural stone and wood floorings. It is often used as a finishing product on top of a hard concrete base and can also be used to encase underfloor heating pipes.