In the Polish market a ready-made roof structure means at least two different products sold under one name — and counting the traditional carpentry it is compared against, three different things. That is where most of the confusion at the ordering stage comes from. One client has in mind trusses clamped together with nail plates and lifted into place by crane in a day and a half. Another has in mind a kit of timber cut at the sawmill to the design and installed in the normal way by a carpenter. The prices of the two can differ by half, and the conditions in which each of them makes sense barely overlap.
We have run a sawmill near Pszczyna since 1990 and we see both solutions every day on the sites of our customers. Below we set out the differences: what distinguishes them, when a ready-made roof structure pays off, and when it is simply the wrong choice.
Ready-made roof structures — three different things under one name
Option A — traditional carpentry-built roof structure. The carpenter receives timber in standard lengths and makes all the cuts and joints on site, following the design and measurements taken from the building. Full flexibility, the longest timescale, the most waste.
Option B — prefabricated trusses on nail plates. Complete flat trusses, pressed together in the works under a force of 18–50 tonnes using steel plates made of 1–2 mm sheet with teeth 8–20 mm long. There is no glue in this technology: the teeth are pressed into the fibres. The trusses arrive on a trailer and are lifted by crane, at 80–150 cm centres — each one carries load on its own, unlike a traditional roof structure, where the rafters do sit at 80–100 cm but bear on principal trusses spaced 3–4.5 m apart.
Option C — a kit cut to size at the sawmill. The sawmill receives the structural design, cuts every element to its final dimension, makes the angled cuts, prepares the joints and delivers a packaged kit. Installation is carried out by a carpentry crew — usually without a crane, because the elements are lifted one at a time; for long purlins and large-section beams the lorry-mounted crane is enough.
Option C most often suits the Polish single-family house with a habitable attic — and it is the one least often mentioned in a conversation about what is on offer.
| Criterion | A. Traditional | B. Prefabricated trusses | C. Sawmill kit |
|---|---|---|---|
| Where it is made | 100% on site | 100% in the works | cutting in the works, assembly on site |
| Joints | carpentry joints plus fasteners | nail plates, press | carpentry joints plus fasteners |
| Equipment on site | none / lorry crane | crane mandatory | none / lorry crane |
| Habitable attic | considerable freedom (posts and collar beams to suit the layout) | special trusses only | considerable freedom (posts and collar beams to suit the layout) |
| Chimneys, dormers | as required | only as designed | as required |
| Installation time | 7–14 days | 1–2 days (up to 4 for complex roofs) | in between |
| Timber consumption | highest | lowest (20–30% less) | as in A, with less waste on site |
| Design required before ordering | yes | absolutely | yes |
One qualification to this table: formally, option C is the same structure as A. The difference lies in where the cutting is done, not in how the roof works.
When a prefabricated ready-made roof structure pays off
Prefabricated trusses have a clearly defined field of application. They work well when:
- the roof is simple and repetitive: gable or hipped, without dormers or bay projections;
- the attic is to remain non-habitable (a cold roof space), and the house is single-storey;
- the span falls within the typical range — 10–12 m for single-family houses; the technology reaches 30 m with simple trusses, but the upper limit always follows from the structural design, not from a catalogue;
- the site programme is critical: installation is finished in 1–2 days instead of 7–14;
- a trailer can reach the plot and a crane can be set up. That is a necessary condition, not a preference;
- no carpentry crew is available. This argument has been carrying more and more weight in recent years.
On top of that comes a real saving in material: a truss uses 20–30% less timber than a carpentry-built roof structure of the same span, because it works as a framework of members rather than a set of beams in bending.
When a prefabricated ready-made roof structure is a bad idea
You will not find this in the sales material, so here it is, point by point.
The attic is to be habitable. The interior of a standard fink truss (the “W” truss) is filled with web members. There is no way to fit a room in there. The answer is scissor trusses or attic trusses, but they cost more and the decision has to be taken at the design stage. On top of that, the loft over ordinary trusses is often designed for an imposed load of around 50 kg/m², that is, not for storing things but for a technician to walk across.
The roof has several slopes, dormers and a number of chimneys. Every opening means a trimmer and a special truss. In market price lists the cost of the material then shifts from the lower half of the range to the upper half, and often above it — and the cost advantage over carpentry melts away.
There is no access for a trailer and no room for a crane. A truss with an 11 m span has to be delivered and lifted somehow.
It is an extension, an outbuilding, or the replacement of a roof structure in an existing building. The geometry then comes from measurements taken on site, not from a design. Prefabrication requires the opposite order.
Something may still change. A truss is a closed system. Once it is installed, nothing in it may be cut. Cutting out web members to make room for heat recovery ducting, a chimney or loft stairs is one of the most frequently reported in-service mistakes made with nail-plate structures. Weakening a section in a truss is not a local matter — it changes the way the whole system works.
Not sure which option fits your project? Send us your roof plan and we will tell you straight whether a kit cut to size or prefabricated trusses make more sense in your case. We have been cutting C24 structural pine and spruce near Pszczyna since 1990. See our offer roof structures or write to us.
The sawmill-cut kit — the option nobody writes about
The third route combines the accuracy of the works with the flexibility of carpentry. The timber leaves the sawmill cut to size, in class C24, at a controlled moisture content, with the angled cuts already made. What remains on site is assembly — usually without a crane, because the elements are lifted one at a time; for long purlins and large-section beams the lorry-mounted crane is enough.
This option makes sense when:
- the attic is to be habitable and you do not want truss compromises;
- the roof is complex, but you want to limit waste and shorten the labour;
- the plot is tight, or access rules out a crane;
- you have a carpentry crew you trust and want to give them timber cut to size rather than cut by eye;
- you are building an extension or replacing an old roof structure.
There is one condition, and it is absolute: a structural design and measurements taken on site are required. Walls never come out to the centimetre, and an element cut in the works to the design has to fit the actual wall, not the drawing.
When a kit cut to size does not make sense. When there is no detailed design — the architectural design alone is not enough for cutting. When the walls are not up and no site measurements can be taken. When you want a single document covering the whole structure: a cut kit is a construction material with CE marking on the timber, not a product with a declaration of performance for a finished component. And when you have no crew — cutting in the works does not replace assembly, it only shortens it.
How much a ready-made roof structure costs
The table below is a review of rates published on Polish trade sites in 2025 and 2026. It is neither an offer nor a price list — the actual price depends on the design, the geometry of the roof, the timber sections and the location of the site.
| Item | Market range |
|---|---|
| C24 structural timber (material) | PLN 1,600–2,200/m³ |
| Traditional roof structure, gable roof (complete) | PLN 150–250/m² |
| Traditional roof structure, multi-slope roof (complete) | PLN 220–330/m² |
| Prefabricated trusses — material only | PLN 110–170/m² |
| Trusses — material plus installation with a crane | PLN 160–240/m² |
| Installation of a traditional roof structure, Silesian Voivodeship | PLN 63–73/m² net |
| Installation of prefabricated trusses | PLN 20–30/m² |
| Crane hire, Silesia | PLN 200–320/h net |
| Wood preservation | PLN 5–7/m² |
Where does the spread from PLN 110 to PLN 330 per square metre of the same “product” come from? From three things worth asking about in every quotation:
- Net or gross.
- Per m² of roof slope or per m² of building footprint. That can be a difference of around 40%.
- Whether transport, preservative treatment and the crane are included in the price, or whether they are charged separately.
We set out a detailed breakdown of the cost of the structure itself in the article on how much a roof structure costs.
Prefabrication does not shorten the whole process as much as the leaflets suggest. Installation, yes — 1–2 days instead of two weeks. But production and delivery take 1–2 weeks, and at the peak of the season as much as 4–8 weeks. Prefabrication moves time from the site into the production queue. The real benefit is shorter exposure of the structure to rain and a lower crew cost, not a calendar counted from zero.
What happens to the timber between delivery and installation
A ready-made roof structure arrives on site all at once, and either there is somewhere to put it or there is not. This stage generates more losses than the installation itself.
Before ordering, check three things: the width and turning radius of the access (a trailer carrying 11-metre trusses needs a proper road and room to manoeuvre), somewhere to unload and who unloads and with what — the lorry-mounted crane or a mobile crane, and how long the delivery can wait.
On site the timber is stacked on bearers, on level ground. Elements laid straight on the ground or on uneven supports take on permanent deformations that cannot be straightened out afterwards — and with a kit cut to size a deformed beam no longer fits its seat. The whole stack has to be covered, but so that air can move: film pulled tight over a pack turns it into a steam chamber. Rain washes out the preservative and starts the first pockets of biological decay before installation even begins.
Once the structure is up, the roof is closed with a membrane as quickly as possible. A roof structure that stands in the rain for a month goes under the covering wet — and gives back the time saved by prefabrication with interest.
What the standard guarantees — and which documents to ask for
Prefabricated trusses are a construction product and are covered by the standard PN-EN 14250. The manufacturer works under system 2+ for assessing constancy of performance, operates Factory Production Control and holds an FPC certificate issued by a notified body. What that means for the client: the trusses must have a declaration of performance (DoP) and CE marking — the absence of either document disqualifies the delivery. The nail plates themselves also carry their own declaration to PN-EN 14545, so this cannot be just any perforated sheet metal.
A sawmill-cut kit, by contrast, is a construction material: the CE marking covers the structural timber to PN-EN 14081-1, and the strength class is defined by PN-EN 338. In both cases the structural calculations follow Eurocode 5 (PN-EN 1995).
Moisture content matters here all the more, the more precise the prefabrication. The market threshold for a roof structure is 18–20%, and the lower the better: an element cut to the millimetre at 25% moisture content simply stops fitting once it dries. Wet timber warps, splits along the grain and loosens joints — and in trusses the teeth of the plates lose their anchorage at exactly the point where the whole node works.
Frequently asked questions
Is a ready-made roof structure cheaper than a traditional one?
On a simple roof usually yes, but the difference comes from labour and a smaller volume of timber, not from the price per cubic metre — you are buying the same C24, only less of it. Trusses use 20–30% less timber, and trade price lists put their installation at around PLN 20–30/m² against PLN 50–60/m² for a traditional roof structure in nationwide price lists (in the Silesian Voivodeship local rates can be higher, of the order of PLN 65–70/m² net) and PLN 60–100/m² for a complex structure. On a multi-slope roof with dormers the advantage melts away or disappears, and the crane is added to the bill — rates published for Silesia in 2026 are PLN 200–320 per hour net.
How long does installing a ready-made roof structure take?
Prefabricated trusses go up on a typical single-family house in 1–2 days, and on more elaborate projects in up to four. A traditional roof structure takes 7–14 days on a simple roof and up to three weeks on a complex one. Production lead time has to be added, though: 1–2 weeks out of season, 4–8 weeks at the peak.
Can a habitable attic be made under trusses?
Not under a standard fink truss — its interior is filled with web members, and the loft is sometimes designed for an imposed load of around 50 kg/m². The answer is scissor trusses or attic trusses, which give open space without posts, but they cost more and require a decision at the design stage. For an unusual habitable attic, a kit cut to size with carpentry installation usually makes more sense.
What timber should a ready-made roof structure contain?
Strength-graded softwood of class C24 to PN-EN 338: characteristic bending strength 24 MPa, modulus of elasticity 11 GPa, mean density 420 kg/m³. Moisture content 20% at most, below 18% recommended. Ask for a document confirming the class — the word “C24” in a quotation is not grading in itself.
What do I need to prepare in order to get a quotation?
The minimum is a roof plan with dimensions, the pitch of the slopes and the positions of chimneys and roof windows. Beyond that: the type of covering planned (because it determines the load), the intended use of the attic, the spans and the layout of load-bearing walls, and for trusses, confirmation that a trailer can reach the plot and a crane can be set up. Add to that the three check questions from the section on prices, which settle most of the discrepancies between quotations.
A ready-made roof structure is neither better nor worse than a traditional one — it is the answer to a different question. If you have a design and want to know which option works out cheaper in your particular case, send us your roof plan. We will price a kit of C24 timber cut to size and tell you honestly when trusses are the better route.
