Roof battens are thin strips of treated timber fixed across the rafters of a pitched roof. Tiles or slates are fixed to them, holding the covering in place, setting the spacing between rows, and transferring the load back to the roof structure. In UK homes, roofing battens are normally graded softwood, most often 25x38mm or 25x50mm, and they should be marked to BS 5534.
This guide covers what roof battens do, the main types, the sizes and lengths you will see, and how battens and counter battens differ. It also shows how to spot compliant timber, when to replace battens, whether they can double as a fence, and what to ask a roofer before you agree to a quote.
What Are Roof Battens?
Picture your roof from the inside out. First come the rafters, then a breathable membrane, then (on some roofs) counter battens, then the horizontal battens, and finally the tiles or slates.
The covering is fixed to the battens, not to the rafters. That is the whole role of battens in roofing, and it is why the battens roof tiles rely on are hidden once the job is finished and easy to forget until something goes wrong.
You will sometimes hear them called tiling battens or slating battens. The name changes, but the job does not.
What Are Roof Battens Used For?
So, what are roof battens used for? They have four jobs, and the first is the obvious one.
Fixing tiles at the right spacing
Every tile or slate is fixed to a batten. The distance between battens is called the gauge. It comes from the tile maker’s specification and the roof pitch, and it determines how much each row overlaps the one below.
Get it wrong, and you can end up with exposed fixings, uneven courses or water getting in.
Carrying loads and resisting wind
The battens carry the weight of the covering plus any snow, and they hold tiles down against wind uplift. The fixings only grip as well as the timber does, so poor timber weakens the whole roof.
Since its 2014 revision and later amendment, BS 5534 has been clear that mortar alone should not hold a roof covering in place.
Leaving a gap under the covering
Battens lift the tiles clear of the membrane. That small air space lets moisture evaporate from the underside of the covering. Counter battens add a second, vertical channel, covered below.
Giving roofers a foothold
Roofers often stand on battens while they work. The HSE allows this only when the battens are graded and meet the size and span limits in its guidance, HSG33, along with BS 5534 and NFRC Technical Bulletin 33. Those limits match the batten sections covered below.
The same guidance warns that timber battens deteriorate with age and should not be used as footholds unless a competent person has confirmed they are strong enough. So never walk on them yourself.
Types of Roof Battens
Roof battens come in a few materials, but one dominates. The covering you choose shapes the whole setup, so it helps to understand the main types of roofing materials before you talk to a roofer.
Timber roof battens
Timber roof battens are softwood, pressure-treated against rot and insects. They are light, cheap, and easy to fix in, so most UK homes use these wood battens.
Ordinary timber battens sold for general use are a different product, and the BS 5534 section below explains why.
Metal battens
Metal battens appear in some commercial, cladding, and specialist slate systems. They hold their shape well and don’t rot, but they only work with compatible fixings, membranes, and coverings. They are not a drop-in swap for timber on a normal house.
Slate battens and tile battens
A slate batten follows the same logic as a tile batten: the size depends on the rafter spacing. Slates are always laid double lap, and natural slates are fixed with nails or hooks. Natural slate suppliers publish their own batten specification, so follow that alongside the sizes in the next section.
Not sure which type matches your roof? Get it checked properly before you spend a penny.
Book A Free InspectionRoof Batten Sizes and Lengths
BS 5534 sets minimum sizes and tolerances. The right choice depends on the covering and how far apart your rafters are.
What size are roof battens?
Graded battens come in two standard sections, both 25mm deep: 25x38mm and 25x50mm. These roof batten sizes are measured at a reference moisture level of 20%, with a small tolerance either way.
The BS 5534 table sets out which one you need:
For spans over 600mm, the standard recommends structural calculations. Your roofer should also check the tile maker’s own specification.
One warning about timber batten sizes: battens sold as 19mm deep fall below the 25mm minimum for roofing use, so they are not roofing battens.
What length are roofing battens?
They are usually supplied at 3.6m or longer. Merchants commonly list 3.6m, 4.2m and 4.8m, and some go up to 5.4m. Once fixed, each batten should be at least 1.2m long and span at least three rafters, which rules out very short offcuts.
Battens and Counter Battens
Battens and counter battens sit at right angles to each other. Counter battens are lengths of timber that run straight down the slope, from ridge to eaves, directly over the rafters. They are commonly 50x25mm up to 50x50mm, and depending on the design, they sit above or below the membrane.
Their job is to keep a continuous channel open from ridge to eaves, so air can move and any water that gets in can drain freely.
A counter-batten roof isn’t always needed. If the membrane is draped over open rafters, the dip between them already forms drainage channels. Some slate roofs fixed to sarking boards also work without them. You’re more likely to need them on low-pitched roofs or where insulation sits close to the covering.
Two things worth knowing:
- Counter battens fully supported by the rafters don’t need grading or marking. If they hold insulation boards or carry structural load, they should be.
- Adding them to an existing roof raises its height, which can affect the fascia, gutters, flashings and roof windows.
BS 5534: What Compliant Roofing Battens Look Like
BS 5534 is the code of practice for slating and tiling. The current version is BS 5534:2014+A2:2018. It is not a law, but a specification; you can cite it to show compliance with Building Regulations, and warranty providers typically expect it. You can find the standard on the BSI website.
Only battens graded to it should be sold or used as roofing battens. Anything else is just sawn, treated timber.
What the marking should show
Each batten should be marked with:
- the supplier
- the origin or species
- “graded BS 5534”
- the size
Simple checks
BS 5534 sets out what a graded batten should look like, and most of it is easy to check by eye:
- Thickness: at least 25mm. Anything thinner should not be used.
- Knots: if a knot shows on both faces, the two sizes added together must not exceed the batten’s width.
- Straightness: no more than 5mm of bow, spring or twist over 1.2m.
- Condition: no rot, decay or growth on new timber.
- Consistency: uneven thicknesses in a stack are a warning sign.
Why colour proves nothing
Many people assume a red, blue or yellow batten must be compliant. Sub-standard battens can be coloured and marked to look genuine. Colour is not proof, and neither is a stamp on its own.
Treatment and paperwork
Roofing battens should also be preservative-treated to Usage Class 2 under BS 8417. Ask for the delivery documents and any third-party certification, and keep the records.
How Roof Battens Are Fitted
A roofer sets out the gauge from the eaves and fixes each batten across rafters that are no more than 600mm apart. Joints are made directly over a rafter, with the ends square cut and tightly butted. This is not a job to try from a ladder. The HSE says roof work accounts for a quarter of all construction industry deaths.
Roof Battens for Fencing
Graded roofing battens are treated for a covered, mostly dry position under the tiles, not for open weather or ground contact, so they are a poor fit for anything structural in a garden. For posts, rails and panels, choose timber sold for fencing.
Light decorative screening is different. Suppliers also sell similar-looking battens that aren’t graded for roofing, and people often use them for a DIY roof-batten fence, such as a horizontal slatted screen.
What to Ask Your Roofer About Battens
Once you know the checks above, the best move is to get the answers into the quote. Ask:
At Hibbs Roofing and Building Ltd, we handle roof installation services across Ashford and Kent, and we are happy to talk through the batten specification before any work starts. You can book a free, no-obligation quote whenever you are ready.
Book A Free Inspection →