I am converting part of a garage to utility area and want to raise the floor to house floor level. (The area is to be sealed from the garage with fire break.) My idea is to make footings from two 45x95 timbers resting on mortar beds onto the existing concrete floor then lay joists over these (more 45x95 being sufficient for the span). So a 10mm mortar bed would give a total of 150mm before boards and covering. First question - is a footing like this acceptable?
The problem is that the existing concrete is not level, with a corner/corner height difference of 21mm. Ending up with over 30mm of mortar in places seems a bit thick and tamping things down to achieve a level is always difficult. So I would lay the two timbers down in the mortar, accept any irregularity then individually set the height of each joist using spacers. The plastic spacers used around window frames seem like ideal candidates. Any reason why they are not? If not, any suggestion?
The problem is that the existing concrete is not level, with a corner/corner height difference of 21mm. Ending up with over 30mm of mortar in places seems a bit thick and tamping things down to achieve a level is always difficult. So I would lay the two timbers down in the mortar, accept any irregularity then individually set the height of each joist using spacers. The plastic spacers used around window frames seem like ideal candidates. Any reason why they are not? If not, any suggestion?