Hi, I’m about to screed my first upstairs room on a project. The room is approx 4m x 4.5m. Floor makeup is: 22mm egger flooring 9mm ply 20mm wunda xps dense grooved boards to take pipes with ufh pipes laid in. Mapei prime grip plus primer over boards and pipes 10mm Mapei renovation 3240 Given that I’m only putting down 8 - 12mm of screed and I have ufh pipes in the grooved boards I’m unable to wear spiked shoes for fear of piercing the pipes. Are there any tips for screeding, and rolling out your footmarks? At the moment I’m planning to: Mix up two bags at a time in a large gorilla trug. Pour the two bags and at the same time have two friends mix up the next two bags and quickly get the next poured maintaining a wet edge at all times. Continue this way until the room is up to level, then use a spiked roller over the entire floor. I’ll of course have to stand in the screed to spike roller the far side. Are there any tips for this or techniques for working over ufh pipes safely? I didn’t think a depth rake would be really useful as it might catch the pipes and I’m only laying 10mm. Aiming to get the floor as flat as possible for LVT directly on top. Any tips appreciated. Thanks Sent from my iPhone using Tapatalk
Personally I would do it in 2-3 coats. Then you can just drop it on the floor and keep building up. The first coat will not hit 10mm as it drops Into and around the pipes.
Have you checked with wunda you can level over these boards and install LVT? They normally Need a plywood fixed over the top? I cant see xps boards being strong enough for leveling compound and LVT.
Yes, wounds recommends either lvt or porcelain tiles over. They do say you can tile directly ontop without screen, but I don’t fancy that. The boards are 400kpa so very dense. A normal marmox or delta cement tiling board is 300kpa. Sent from my iPhone using Tapatalk
As merit says, I'd do this in 2 coats. You'll probably end up wanting to top it up anyway after you've tried and drop 10mm in one hit so just flow forst coat over and fine tune it with the 2nd coat couple days after. Remember to prime between the 2 coats
I've done 15mm over 30mm xps before and been fine. Manufacturers had to proper convince me though before I was confident in doing so
I asked the reps from both Mapei and instarmac about laying in two goes as to me that’s way easier. They suggested that might form a weakness in the screed that could de-bond? Can I ask why LVT on-top might not be a good idea? I’m planning heat resistant adhesive. My original plan was actually porcelain tiles, but I figured LVT would cope with any fractional movement better and also be less weight on the floors. Thanks for all tips. Sent from my iPhone using Tapatalk
Yeah ive noticed alot of manufacturers stating it has to be done in one pour. Another reason im not convinced about the whole system. As long as you follow what they say you should be fine. Get it in writing
Well one rep previously from instarmac, suggested it was fine to pour in two. I did figure that if the primer was tested to prime the aluminium cos boards, surely it’s fine to prime screed to screed for a second pour?… If I was to go for the one pour, are there any tips for carrying it out, smoothing / rolling out footprints and ensuring I have as level a finished floor as possible? Again the spiked shoes would be the answer but not possible with the pipes. Cheers Sent from my iPhone using Tapatalk
I've always poured in 2 coats, so much easier and less stress but I've also done one pout of 12mm which I had to go over again anyway because I wasn't happy with the finish. By time I patched up with feather it was just so much easier to flow another fine coat. I have found that most reps are suggesting 1 pour but way I see it is providing you give it 24-48hrs and the right priming then it's OK. Without being able to go over with your spikey shoes then I'd suggest 2 pours mate, you'll get into a riiiiiiight mess by stamping your flat feet all over it even if you work backwards you can cause the slightest waves. I wouldn't do it myself but I imagine there is some that do it.
Just for the record I've done also done 3 pours and with all multiple coats I've done over the years I've never had a failure [touch big fat hairy wood]
This makes much more sense! Get one base coat on of 6 - 8mm to cover the pipes. Let that go for a week, then get another thinner on top with spiked shoes and the spiked roller again. I’ve been advised Mapei prime grip plus which has grit in for the first primer coat as we’re covering aluminium shiny xps grooved boards. Would you recommend the same primer for the second coat or something like a non grit msp? Thanks for all the advice. Much appreciated. Sent from my iPhone using Tapatalk
When I use reno I always primgrip on the cement boards/xps (whether there is pipes present or not, even over electric mats) then 2nd coats I've used 2 separate coats off primT (1 coat each direction) Just let the primer dry properly and you'll be fine. This is always the system I've used for years with no issues at all pal
Ii usually do 2 coats, the first one is mainly to fill in the deep spots and seal the floor, just in case the screed finds it way under the xps
Paul - have you ever had an issue with the xps aluminium reacting with the cement in the screed? I’ve been warned about it. Apparently the primer is the separation layer to stop the reaction. Sent from my iPhone using Tapatalk
Just wanted to thank you all for your help and advice on my first big screed. Done 90m2 with Mapei renovation screed and it went down a dream. Done the first 9mm in one pour and have the second 6mm pour to go down next although it’s already very flat. The Midwest screed rake recommended was great as was the spiked roller and tips on getting it in and mixing up. Going to start a new thread on Amtico parquet with a border (which I’ve never done before) hopefully for some laying tips and pattern ideas at doorways. Thanks to everyone who advised. Sent from my iPhone using Tapatalk
