How level must concrete floor be for Engineered Flooring

BarraOG

Hi,

I'm exploring the idea of laying a Haro 3000 Engineered Floor in some of our bedrooms:

https://www.haro.com/en/products/parquet/longstrip-oak-favorit/index.php

The bedrooms are on the ground floor which is concrete. The house was built 10 years ago. When I sat a large spirit level on the floor, it rocks at some locations on the floor by a few millimetres. Also if I walk on the floor I can feel slight depressions under foot. How can I establish if the concrete floor is ok in its current state?

Thanks,

Barra

Calahonda52

What underlay are you using?
Are u using the recommended one?
what is a large s/level: 1.8m or what.
A couple of mm per m is usually okay but you should really ask them

BarraOG

Calahonda52 wrote: »

What underlay are you using?
Are u using the recommended one?
what is a large s/level: 1.8m or what.
A couple of mm per m is usually okay but you should really ask them

The spirit level was around a yard in length. I'm buying from a local retailer who has sourced this floor for me for a good price but they normally don't specialise in it. Therefore they won't be able to offer me specific advice regarding the floor I'd image. What I'll do is contact whiteriver who are the importers of this floor and ask them.

sky6

Use Self levelling compound to remove any imperfections. Then with a decent underlay you should have no problems.

ondablade

Presuming you mean the laminated boards that are glued togther and laid over a polyethylene foam 'spring' layer. This is one of those jobs that's worth getting right as you will live with the consequences afterwards.

It's normal to spec flatness in terms of a few mm/metre, but this overlooks the reality that dips/troughs may be of small enough diameter/width that the flooring may bridge it and be part unsupported. Flatness within a mm or two is fine, but the changes in height need to be very gradual given this effect.

Bridging and irregularities will lead to a risk of squeaking and loosening over time as well as raised edges/corners and enough irregularity to drive you nuts over the years. Chairs and tables will rock, and you will feel it under your feet.

My best advice based on experience is also to get a good job done with a levelling compound - one of the expensive but high quality German ones that flow well and will feather out almost to nothing. Proper cleaning and priming of the floor first matter. Fill deep hollows first using a compound designed to handle greater thicknesses/depths.

Survey the floor first with a level and a long straight edge, or possibly with a rotating laser level. Decide whether or not the high point is acceptable (since this sets the level for the rest of the floor), bearing in mind the required floor levels in adjacent rooms and whether or not you can live with a step or timber saddle board. Grind or chisel off high areas if required - with luck they may not be that large.

It's not typical these days, but beware of doing too much aggressive hammering if the floor is a lean mix sand/cement screed over a structural slab - it could start to crack.

None of these compounds truly self level, so putting them down is a skilled job. Most won't take the trouble to do so, but a good method is to drive masonry nails in a grid pattern at maybe 600mm spacings. Set your floor height (whatever you know from checking will be the highest point in the floor) and start from there. Drive the nails so that the head is at the required surface level, use a (good) spirit level or laser to set the height of the next. etc etc

Then screed out the levelling compound using a length of aluminium angle or something else straight and not too heavy to handle - leave it so that all the nail heads are just visible.

This method works very well, especially if you haven't a lot of experience but are prepared to invest time...

BarraOG

Thanks for your reply! Would you mind PMing me the names of the levelling compounds you'd recommend? I presume they are letex.