Natural Stone Floor - Showing signs of damp?

Question

We live in an old house with a natural stone floor. The floor is showing signs of damp coming through. Upon lifting the stones we have discovered that they are laying on wet earth; no plastic membrane and no cement base.

We have researched some books which say that there are two alternatives to go for in order to deal with this problem.

Option One: Lift stones, lay plastic membrane, install a layer of lime/sand mix sub floor base and then relay stones. (This options seems somehow not sympathetic to the old building as the dpm may cause dampness to be directed to the exterior walls).

Option Two: Lift stones, install deep bed of stone shingle, install layer of lime/sand mix sub floor base and then relay stones. (This method would seem sympathetic to the old building and would allow the floor to "breath").

Which method would be best practise - or is there another method better than these maybe?

Thank you

Answer 1

G'day, without a moisture barrier (builders plastic etc) (as in option 2) you will always get moisture seeping through, option 1 is the better way to go, when you lay the plastic make sure the overlap is at least 12 inches wide and secure with duct tape the whole length of the joins, run the plastic as far as possible to the walls and even past the perimeter if possible (I'm guessing the house is on stumps as the floor is on bare earth) (best solution)! if getting past the walls is not possible, about a foot from them angle the plastic into the ground so it'll create a rough umbrella style border, I wouldn't worry about the dampness being directed at the walls though as they've been there a while and would've seen their fair share of moisture and still standing. The only other way I can recall is to clean and seal each stone on the base and sides (so it won't ruin the look) and use a flexible sealant for in between (though you'd have to be sure the ground is very hard and level again after digging up the stone) hope this helps and good luck

Answer 2

I lived in Burnley for a while same problem no possibility of puttin in a dpf so you use render either mixed 1-1 s/c or with a dampproofing additive and their recommendations for the mix. do one scratch coat and be sure not to scratch right the way back to the stone - just enough scratch to give you a key . Take the render at least a foot higher than the damp rises. Then get a second coat as soon as you can get back on it - if you leave it too long - the first one will be rock hard and you r second coat will end up sliding on the floor. The additive makes it a bit like smearing melted cheese around but it works. You need also to not have the rendering touching a screed floor at the bottom end so it needs to be cut away when still soft. This worked on the stone cottages in Burnley - also make sure that if you have a screed floor that you have a dpm in place otherwise that will wick damp up your walls

Answer 3

Rossco is absolutely correct! You must install a vapor barrier or plastic membrane, being sure that it is a tight sealed envelope to your substrate for your stone floor. All seams and sides are sealed, then any type of gravel, crushed limestone, stone dust or concrete over the top for a good solid floor base.



Good Luck...



Tom A

Sr. Construction Manager

Albion, Michigan USA

Answer 4

lift the floor ..excavate 200mm ..buy a plastic land-drain ..a pipe with 100s of holes in it ..lay it around floor area .....form hole in wall to allow end of pipe to be outside ..this pipe at lowest exterior ground level ..to allow free drainage ...the pipe is normally 100mm diameter ...lay 150 mm hardcore .blind it with sand ..1200 gauge membrane ....this should leave you still 50mm lower than FFL ..mix a good sand cement lime mortar and re bed slabs