Typical UK Floor and Roof Loads: Dead and Imposed (kN/m²)
10 October 2026 · 8 min read
Typical UK floor and roof loads in kN/m²: imposed values from the National Annex, dead loads for common build-ups, and a loft conversion worked through.
For a typical UK house, a timber floor carries about 0.5 to 0.8 kN/m² dead load and 1.5 kN/m² imposed load (plus a partition allowance), a solid concrete floor about 3 to 5 kN/m² dead, and a tiled pitched roof about 0.6 to 1.0 kN/m² dead with 0.6 kN/m² imposed. These are characteristic values, before any factors are applied.
Search results for this question mix Danish, Indian and American codes, and quote kg/m² next to kN/m² as if they were the same thing. This page sticks to UK practice: BS EN 1991-1-1 with its UK National Annex.
What are the typical loads at a glance?
| Element | Dead load (kN/m²) | Imposed load (kN/m²) |
|---|---|---|
| Timber joist floor, boards and plasterboard ceiling | 0.5 to 0.8 | 1.5 (plus partitions) |
| Beam and block floor with screed | 3.5 to 4.5 | 1.5 (plus partitions) |
| 150 mm solid concrete slab with screed and finishes | 4.8 to 5.2 | 1.5 to 2.0 |
| Pitched tiled roof, on plan | 0.6 to 1.0 | 0.6 (not accessible) |
| Flat roof, timber warm deck | 0.5 to 0.9 | 0.6 (not accessible) |
| Loft floor, storage only | 0.25 to 0.5 | 0.25 to 1.5 (see below) |
Values are typical and must be checked by a competent engineer for design. Manufacturer data beats any table in a blog post.
What imposed load should I use for a floor or roof?
Imposed load (also called live load) depends on how the space is used, not on what it is built from. The values below are from BS EN 1991-1-1 with its UK National Annex. Each category has a uniformly distributed load (qk) and a concentrated load (Qk) that you check separately, not together.
| Use | Category | qk (kN/m²) | Qk (kN) |
|---|---|---|---|
| Domestic floors, bedrooms, living rooms, kitchens | A | 1.5 | 2.0 |
| Stairs and landings inside a single dwelling | A | 1.5 | 2.0 |
| Offices | B | 2.5 | 2.7 |
| Shops | D1 | 4.0 | 3.6 |
| Roofs not accessible except for maintenance, up to 30 degrees | H | 0.6 | 0.9 |
Source: UK National Annex to BS EN 1991-1-1. Check the full tables for sub-categories: communal stairs, balconies, assembly areas and car parks all have their own, higher values.
Three points that catch people out:
- Concentrated loads act on a small square, not the whole floor. The Eurocode area is 50 mm by 50 mm, and you check it against the local capacity of the deck or board, not the beam.
- Roof imposed load is not added to snow. The 0.6 kN/m² maintenance load and the snow load are not taken together. Snow on the ground is site-specific (altitude and region) and comes from BS EN 1991-1-3 and its National Annex, so it is outside this page.
- Partitions are separate. Domestic floors with movable partitions need an added allowance. BS EN 1991-1-1 (clause 6.3.1.2) gives 0.5 kN/m² for partitions weighing up to 1.0 kN/m of wall, 0.8 kN/m² for up to 2.0 kN/m, and 1.2 kN/m² for up to 3.0 kN/m. A standard stud partition is usually in the first or second band.
What are typical dead loads for floors?
Dead load (permanent load) is the weight of the structure and finishes. You build it up layer by layer from unit weights: reinforced concrete is taken as 25 kN/m³, normal concrete 24 kN/m³, and screed about 22 to 24 kN/m³ (BS EN 1991-1-1, Annex A).
| Floor build-up | Dead load (kN/m²) |
|---|---|
| Timber joists at 400 centres, 22 mm boards, 12.5 mm plasterboard ceiling | 0.5 to 0.8 |
| Solid concrete slab, per 100 mm thickness (at 25 kN/m³) | 2.5 |
| 150 mm solid slab | 3.75 |
| 200 mm solid slab | 5.0 |
| Screed, per 50 mm thickness | 1.1 to 1.2 |
| Beam and block, 150 mm deep (without screed) | about 2.0 to 3.0 |
| Ceiling, 12.5 mm plasterboard and skim | about 0.15 |
| Floor finishes and services allowance | 0.2 to 0.5 |
Sources: BS EN 1991-1-1 Annex A for unit weights, with build-ups worked out from them. Beam and block depends on block density and beam spacing, so use the manufacturer's data rather than the range above.
A 150 mm slab with 65 mm of screed and light finishes comes to roughly 3.75 + 1.4 + 0.3 = 5.5 kN/m². The 4.8 to 5.2 kN/m² in the summary table assumes a thinner screed. Write down the build-up you actually used. It is the part a checker will want to see.
What are typical dead loads for roofs?
Roof dead loads are normally quoted per m² of roof surface and then converted to plan area, because the takedown works in plan. Divide the slope value by the cosine of the pitch. At 35 degrees that is ÷ 0.82, or about 22 per cent more.
| Roof build-up | Dead load (kN/m²) |
|---|---|
| Concrete interlocking tiles with battens and felt, on slope | 0.5 to 0.7 |
| Clay plain tiles with battens and felt, on slope | 0.6 to 0.8 |
| Natural slate with battens and felt, on slope | 0.3 to 0.5 |
| Trussed rafters or rafters, insulation and plasterboard ceiling | 0.3 to 0.4 |
| Pitched tiled roof, complete, on plan | 0.6 to 1.0 |
| Flat roof, timber joists, warm deck with felt or single ply | 0.5 to 0.9 |
Source: unit weights from BS EN 1991-1-1 Annex A and BS 648 historical values, with the build-ups assembled from them. Tile weights vary a lot between products, so check the manufacturer's data sheet. A slate roof on a heavy timber structure can land close to a lightweight tiled one.
If the flat roof has gravel ballast or a green roof, add it. Ballast at 50 mm is about 1 kN/m², and a green roof can be several times more.
Worked example: converting a loft
A common problem. The house has existing ceiling joists spanning 4.0 m, and the client wants to use the loft as a bedroom. Those joists were sized as a ceiling with minimal storage, so the question is how much more load the floor now has to carry.
Existing ceiling joists (not accessible, light storage):
Dead = 0.25 kN/m²
Imposed = 0.25 kN/m²
Total = 0.50 kN/m² characteristic
ULS = 1.35 × 0.25 + 1.5 × 0.25 = 0.71 kN/m²
New loft floor (bedroom, domestic category A):
Dead = 0.65 kN/m² (boards, joists, ceiling, insulation)
Imposed = 1.5 + 0.5 = 2.0 kN/m² (floor plus light partition allowance)
Total = 2.65 kN/m² characteristic
ULS = 1.35 × 0.65 + 1.5 × 2.0 = 3.88 kN/m²
The ultimate load goes up by a factor of about 5.5. That is why existing ceiling joists are almost never reused as the new floor. They get new floor joists, usually deeper, often resting on new steel beams or on the existing walls through padstones.
Joists spanning 4.0 m load each support with half the span, so the line load on each wall is:
Line load = 2.0 m × 2.65 = 5.3 kN/m characteristic
That is before the extra roof loads, the dormer, and any steel beam point loads picked up on the way. Check the walls and foundations below, not just the joists.
Characteristic or design load?
Everything in the tables above is characteristic: the unfactored value. For ultimate limit state checks, the usual starting point is 1.35 × permanent plus 1.5 × variable (expression 6.10 of BS EN 1990). The UK National Annex also allows expressions 6.10a and 6.10b, which usually give a slightly lower figure. For service checks such as deflection and bearing pressure, use the characteristic values. Characteristic vs design loads takes the same wall down both ways.
How do these loads feed a load takedown?
Each value above is an area load. A takedown turns it into a line load or a point load by multiplying by the width of floor the element picks up.
Line load (kN/m) = area load (kN/m²) × loaded width (m)
So a 1.5 kN/m² imposed load on a floor spanning 4.0 m gives 3.0 kN/m imposed on each wall, before dead load and before wall self-weight. The manual load takedown article goes through the whole walk from roof to foundation, and the loaded width article covers how to set out the strip for cantilevers, continuity and awkward plans.
Build up the area load from its layers once, put it on the sheet with its source, and reuse it everywhere. Most errors in a takedown come from mixing up the loads at this stage, not from the arithmetic after it.
If you would rather not repeat this for every wall on every level, you can do the whole building in LoadTakedown, where each floor and roof carries its own build-up and the loads accumulate down the walls for you.
FAQ
What is the imposed load on a domestic floor in the UK?
The UK National Annex to BS EN 1991-1-1 gives 1.5 kN/m² for domestic floors (category A), with a 2.0 kN concentrated load checked separately. Add an allowance for movable partitions, usually 0.5 to 0.8 kN/m² depending on the partition weight. Stairs and landings inside a single dwelling take the same 1.5 kN/m²; communal stairs and balconies have higher values.
What is the dead load of a timber floor in kN/m²?
A typical timber joist floor with 22 mm boards and a plasterboard ceiling weighs 0.5 to 0.8 kN/m². The lower figure covers lightweight joists and thin boards. Add more for heavy finishes, deeper joists, insulation, pugging or services. The sum of the layers is more reliable than a rule of thumb.
How much does a concrete slab weigh per m²?
Reinforced concrete is taken as 25 kN/m³, so a slab weighs 2.5 kN/m² for every 100 mm of thickness. A 150 mm slab is 3.75 kN/m² and a 200 mm slab is 5.0 kN/m². Add screed (about 1.1 to 1.2 kN/m² per 50 mm) and finishes. Divide by 9.81 if you need tonnes per m², but design in kN.
What load can a loft floor take?
It depends entirely on how the joists were designed. Existing ceiling joists in a loft are typically designed for about 0.25 kN/m² imposed load, which does not allow for bedrooms or heavy storage. A habitable floor needs at least 1.5 kN/m² plus partitions, so a structural check or new joists are almost always required.
Do I add snow load to the roof imposed load?
No. The 0.6 kN/m² roof maintenance load is not combined with snow. Snow is site-specific, because it varies with altitude and region, and comes from BS EN 1991-1-3 and its UK National Annex. Use whichever of the two governs, but always check the concentrated 0.9 kN load for the roof covering.