Plywood underlay question for laminate

[liamruairi]

Ok, please bear with me on this one! Looking for confirmation that my plan is the right one...
Planning to laminate the downstairs of house, (1908 Sheffield semi - wonky floors a-go-go). Have had wall including fireplace and chimney beast removed between kitchen and dining room leaving gaping hole, exposed concrete hearth, etc not to mention height level discrepancies between the two subfloors where they meet. Also hallway is very slanted, 30mm down the left lower than the right side.

My plan is this; please advise...
Level hearth with self levelling compound and fill chimney with concrete (load of earth in it at moment) then put dpm over that bit.

18mm exterior ply over the lot, screwed down at 6' (2' along edges) except in hallway 12mm ply with battens down one side to try level floor. (My idea here is the living room being 18mm and the hallway 12mm there will be less of a step).
Cover the plywood then in fibreboard underlay like this: http://www.diy.com/departments/dial...98_BQ&ef_id=UhEpVgAAAB6LRzmG:20150224081639:s

Then laminate over.


Is this the right way to go?

Many thanks in advance folks
Liam

 

[ree]

Why not post pics of the areas you've mentioned?

Check all the suspended floors for sway or bounce.

You would do well to crawl under the floor(s) and examine the joist tails that are seated in the brickwork - find out why any joist is sagging.
It could be down to fungal rot or lost packings.
If the hallway is difficult to access, then come back here.
You could also check the hearth trimming joists for fungal damage.

As regards the hearth and fire opening area, it would be best to crack out any existing concrete hearth, and dig down a little below any wood plates or lower than the bottom edge of any hearth trimming joists.
The soil will be contained in a fender wall.

Its best practice to replace the concrete with wood suspended over the old hearth area.

After the above we can advise you ref the height differences between floors.

 

[liamruairi]

thanks ree; there is a cellar underneath the whole floor so access is no problem. The uneveness / slantiness isn't due to joists rotting etc its just settlement over the last 100 years most houses in this area have a similar problem. Flooring is mostly solid and even except where rooms meet. I'll post pics later to give a better idea.
Cheers

 

[liamruairi]

Here's a pic of the floor. As you can see the chimney 'hole' has been covered with some temporary floor boards for safety at the moment and in front of that is the old hearth base, which sits around 4mm lower than rest of the floor. On the other side of the temporary floor boards is a square of concrete which was a hard standing for the old cooker.

I'm thinking levelling compound to bring the hearth up to the same level then bang 18mm plywood over the lot followed by laminate. Any thoughts?
Cheers,
Liam

Untitled

• liamruairi
• 27 Feb 2015
• 1

 

[ree]

Seems a reasonable way to go. But be cautious that raising FFL's doesn't trap the appliances and units in the kitchen, and cause difficulties at door thresholds?

FWIW: I've seen Laminate laid over underlay on T&G boards without any ply and its also worked out fine.
Ideally, the floor should be perfectly level and flat with ply or similar but its not always possible so one does the best one can.

 

[liamruairi]

Cheers, it's a total refurb so floor is going to be raised all downstairs and new doors will be fitted. I'm only going to floor up to the kitchen units (not underneath) and retro fit the plinth/kick board once floor is in so shouldn't be a problem.
Thanks!

 

[ree]

I think that you may have misunderstood: the future difficulties of flooring up to Apps and units is how will you get them out if it becomes necessary for repairs etc.

Perhaps you have adjustable legs on all items but if not, its worth thinking about.

 

[liamruairi]

yes they all have adjustable legs, and will be putting new floor under appliances, just not under units. Kitchen is brand new and I expect it to far outlast the floor.
Thanks!