Latex or water?

[exburyman]

I need to re-level a concrete floor on which I shall be laying a solid wood floor. The floor will be glued to the new surface of the concrete using an adhesive called "Polyurethane 40". Does anyone know whether it would be best to use a standard water-based levelling compound, or a latex-based compound in order for the adhesive to bond?

Also, is the technique for laying either type the same? Is either any easier/harder?

 

[WoodYouLike]

What I do know is that when glueing a (solid) wooden floor on concrete/screed your weakest link is the screed (wood works always and no adhesive will withstand the power of wood expanding in extreme circumstances).
Make sure what ever type of screed you use it has bonded well to the existing concrete floor.
(and rule of thumb: 1 inch of screed/concrete takes 30 days to dry).

 

[exburyman]

woodyoulike,

Thanks you for your reply. The adhesive (Polyurethane 40) is apparently used on motorway bridges at the point where expansion and contraction of the concrete is controlled, so I am fairly confident it has sufficient strength and flexibility to withstand the forces of the wood.

My main question was really aimed at understanding which type of levelling screed would provide the best adhesion both to the sub-floor and the adhesive.

 

[flooringman]

A water based screed, such as F.Balls' Stopgap 300, will give a stronger surface finish than a latex screed.

I would strongly suggest that you use an adhesive that is specifically designed for use with wood floors (ie. flexible) rather than one designed for building bridges.

 

[exburyman]

Thanks flooringman.

The adhesive is designed to include wood flooring installation according to the description on the can. It was recommended to me by a wood floor installation company so I am fairly confident about its suitability. The bridge example is just an example to show its strength and flexibility.

I appreciate your recommendation of Stopgap 300 - can you name a stockist as I cannot see it listed on the more common DIY suppliers websites?

Also, any tips on how to go about applying it for someone who has never attempted such a task before?

 

[flooringman]

You can try a local flooring wholesaler or ring F.Ball 01538 361633 for your nearest stockist.

I use a flooring rake and spiked roller rather than a trowel to spread the screed but it depends on the area you have to cover.

You also need to check the concrete base for moisture content whenever you are glueing down a wood floor - take careful note of Woodulikes' closing comment every posting.

 

[exburyman]

Thanks again flooringman.

I have contacted F.Ball and found a local suplier. However, I have since spoken to another flooring company and they suggest the most appropriate levelling compound would be an 'acrylic' based compound as it is more hard wearing and provdes better adhesion. I now confess to being totally confused as there seem to be a bewildering number of terms used interchangeably for what appear o be similar substances. I have come across compounds described as 'latex', 'acrylic' and 'acrylic latex' based.

Can you shed any light on this?

I thought this was going to be a simple job!

 

[flooringman]

The terms acrylic, latex etc. relate to the type of liquid with which the screed powder is mixed.

If you need to put a liquid dpm down (ie. the existing base is not within moisture tolerance for wood flooring) then you should use an acrylic screed - e.g. Stopgap green bag with '55' before applying the dpm.

In any event the Stopgap 300 will have a higher compression strength than the latex or acrylic screeds.

Hope this helps.

 

[exburyman]

I understand the different mixtures but what I don't understand is in which situation you should use which type.

You imply that an acrylic mix should be used where the moisture level is above tolerance. I have been told from other sources that you should use a latex mix when covering an existing bitumen epoxy in order to get good adhesion. Are there any fixed rules that apply - if so where can I find then written down?

The most common brands seem to be Ardex, Arditex and Febfloor. Do you recommend any of these in preference to any other - I appreciate that you have already recommended Stopgap but it seems less widely available.

 

[flooringman]

Ardex manufacture an excellent range of products and end users will all have their own favourites-I just tend to use F.Balls' products.

You need to determine:

A. The composition of the sub floor.

B. By how much the sub floor needs to be levelled.

C. The moisture level in the existing sub floor.

D. The compatability of the adhesive you are using with any coatings you are applying.

All the main manufacturers have a technical department and I have always found them to be more than helpful (no matter how many times I contact them) although they are all cagey about giving advice on using their own products with other suppliers products.

The supplier of the wood you are purchasing should be able to give the best advice as they will know which adhesives and underlayments are most suitable.

 

[exburyman]

Thanks flooringman, all comments gratefully accepted.

 

[Damo1176]

Quick question what is the highest depth you can put down Stopgap 300 to. I have a drop from one room to another of 15mm at worst and was advised Latex screed can onnly go down to the depth of 6mm. I have used stopgap before and found that anything over 6mm took ages to dry but seemed to do the job.

 

[mattysupra]

why dont you read the sticky at the top of the forum on how to use levelling compound your answers are here. And yes use water based or acrylic!

 

[mattysupra]

damo do it in a couple of coats.