Ideal home: floors on the ground
Floors on the ground
Replacing the wooden floors of the first floor in an old stone house with floors on the ground. Click on photo to enlarge.
Ground floors are ground floor or basement/basement concrete floors that lie “right on the ground”, i.e. there is no air space between the floor and the ground. Floors on the ground are often made if the house is built on a strip foundation, i.e. the floor is poured between the walls of the tape. It is not recommended to build floors on the ground if the site has a high groundwater level.
This floor should be:
- warm
- waterproof from the ground
- relatively durable
Floors on the ground are a multi-layer construction. Each layer performs a specific function. In this regard, floors on the ground are similar to slab foundation.
First, the excess fertile layer of soil is removed and the surface is leveled and rammed. Then a pillow is made: coarse-grained sand is poured, leveled and carefully compacted. Crushed stone from 10 cm is poured on top and is also carefully compacted. A vibrating plate is used for tamping a sand/gravel cushion; it runs on gasoline. If the workers do not have their own vibrating plate, it can be rented (it is inexpensive). Ramming and rolling of crushed stone / sand is very important, in no case should you save on this!
A useful feature of crushed stone is that it does not suck moisture from the soil. The evenness of the pillow must be checked with a laser level.
Many developers make a pillow in different ways: someone only from sand, someone only from crushed stone, someone from a layer of sand, and then a layer of crushed stone. According to reviews, with proper tamping, all of these options work well. I remind you that crushed stone and coarse sand are good non-rocky soils.
A thin concrete rough screed 3-5 cm is made on top of the pillow. Its meaning is to create a flat surface for laying waterproofing and insulation. Accordingly, there is no need to spend money on its reinforcement. After hardening of the rough screed, waterproofing is laid. It can be waterproofing films in two layers or bituminous waterproofing, you need to look at the money and the UGV.
Then insulation is laid - extruded polystyrene foam, which is much more durable than conventional polystyrene foam and can withstand significant loads. Insulation is needed so that the floors are warm, about the same temperature as the air in the room. EPPS also partially performs the function of waterproofing (except for its joints).
It is impossible to compare wall and floor insulation on the ground. In winter, the soil under a residential building with floors on the ground and an insulated blind area has a positive temperature, at least in the European part of Russia. Therefore, EPS 5 cm thick should be enough.
Next, a full-fledged concrete screed 5-10 cm is made on top of the insulation (the thicker, the more load it takes). She will hold the finishing floor, partitions; at the same time, it can be considered a heavy heat accumulator (this is a plus), because it is located between the insulation and the room. Unlike conventional screed over, for example, floor slabs, floor screed on the ground necessarily requires reinforcement (mesh or reinforcement). Usually it is reinforced with a welded mesh 10x10 cm or 15x15 cm with a wire thickness of 3-6 mm.
On top of the main screed, the finishing flooring is already mounted.
I have described one of the popular floor constructions on the ground, although in fact there are several of them. I drew a diagram below:
Here: 1 - main screed (any top coat can be laid on it), 2 - EPPS, 3 - waterproofing, 4 - rough screed, 5 - crushed stone / sand / crushed stone with sand, 6 - natural soil, 7 - strip foundation, 8 - wall.
Please note that the waterproofing goes on the tape, i.e. possible moisture from the soil is completely cut off from the room and walls. Also note that the insulation goes on the tape, i.e., firstly, it partially cuts off the cold coming from the tape, and secondly, it is an expansion joint. But still, it is better to additionally insulate the tape from the outside and the blind area.
An expansion joint is needed if underfloor heating is used, when the concrete screed can heat up sharply from the pipes in it and expand. If there are no warm floors, then a expansion joint is optional.
People often, in order to save money, change the floor construction on the ground. Someone refuses waterproofing and everything is fine: compacted rubble does not suck water upwards, plus groundwater is deep. But it's still risky.
Someone refuses a heater and thereby warms the soil under the house. I would not recommend doing this, with a heater under a concrete screed, heating costs will be lower. I myself have a concrete floor on the ground without insulation, and if I did everything again, I would definitely put the EPPS. It's not about heating costs, but more about comfort, it pulls cold from the floor. If there is a layer of XPS under the concrete, then the floor temperature will be almost the same as the air in the room.
The benefits of flooring on the ground must be calculated. It may turn out that it is cheaper to build ordinary "hanging" floors.
If floors are chosen on the ground, then it is necessary to insulate the basement of the foundation, otherwise you will get a cold bridge at the point of contact of the screed and the base of the tape.
With floors on the ground, of course, arrangements in the strip foundation are not required. But if the foundation is being built and it is not yet clear what will happen - floors or floors on the ground, then it is better to make air vents, and then, if it is decided to still make floors on the ground, air vents can be laid.