DIY Doctor UK DIY Forums

Have started to lay a laminate floor but have found that where there was once a fireplace there is now just a large rectangle of uneven concrete.

Have chipped away most of the concrete so that now is is lower than the level of the floorboards.

I need to fill the space with something to make it the same level as the floorboards but what is the best product to use?

Can I use ready mixed mortar? The depth is up to 15mm - 20mm max in some places.

dont think that there is any such thing as ready mixed mortar.... it sets chemically, not in contact with the air so would just go off in the tub. unless you are referring to the sand/cement mix that you can buy that needs water, in which case that should do the job fine. PVA the existing hearth first so that it bonds properly and make the mix fairly wet so that it levels easier.

a simpler alternative may be levelling compound. on such a small area it wouldnt be much hard work at all. bear in mind that either will take weeks to fully cure.