Laminate - sub flo and underlay advice

[Gille]

Hello again. Thanks to those who have provided me with good advice over the past months. I am looking for any views you may have on the advice I have been given by a local flooring company.

Background:

About 3 months back I added a conservatory to the rear lounge of my
house. I now have one through room (roughly 26'x12'). The lounge floor is made up of 8x2 18mm flooring sheets and the conservatory has a concrete floor. I am happy that the concrete floor has dried out. There is no condensation or other signs of moisture. The conservatory is not South facing and willl not get full sun/heat in the Summer therefore I have decided to have a laminate floor laid.

The laminate I am looking at is by Balterio and is a 9mm board with the 4way v-groove, not cheap but hopefully a good quality board. The fitter has been to see the job and the 2 different sub floors.
There is a difference in level between the old and new floor, not a
noticeable step but more a gradual slope of upto 10mm from the edge of the concrete running away towards the middle of the original lounge. I hope I have explained myself clearly here.

He has suggested:

Laying the board type sheets in the original room (to raise the level)
and then cover the whole area with a standard underlay with a built in dpm for concrete floor - laminate on top and then I will finish the job by fitting new skirting (all old skirting has already been removed).

Does this see seem sensible or could I expect problems in the future.

Cheers

 

[WoodYouLike]

He has suggested:

Laying the board type sheets in the original room (to raise the level)
and then cover the whole area with a standard underlay with a built in dpm for concrete floor - laminate on top and then I will finish the job by fitting new skirting (all old skirting has already been removed).

Does this see seem sensible or could I expect problems in the future.

Yeap, there will be a problem if you don't create one type of underfloor: moist and temperature underneath will be different with concrete and the sheet material.
Also, using DPM on sheet material is asking for condensation trouble.
If your fitter intents to use sheet materials to level the floor to same heights he should use the same material (thinner) in the original room in order to create one type of underfloor and then install underlayment without DPM.
See here for more info on underfloors and type of underlayment to use.

 

[Gille]

Thanks for this, I spoke to another fitter today who has suggested raising the level slightly in the original room by screeding. Is this possible on top of chipboard flooring? I am starting to get a bit worried now about the best approach. Can I not raise the level by putting fibre boards over the chipboard flooring, put a dpm sheet over the concrete floor in the conservatory and then run a standard underlay over the dpm and fibreboards. If photos will help I can sort some out.

Cheers