How Much Does a New Slate Roof Cost in Deeside?

A slate re-roof in Deeside is priced on the same things as anywhere: how many pieces the roof takes, which slate goes on it, how much lead the junctions need, the state of the timbers, and access.

There is one element where being in Wales genuinely changes the job, and it is not the slate. It is what happens underneath.

Where Wales Differs, and Where It Does Not

Slate is bought on the same market either side of the Dee, laid to the same British Standard, and graded under the same European standard. None of that changes at the border.

What does change is the guidance on thermal performance. Wales has its own Approved Document L, and for a new or replacement roof element in an existing dwelling it sets a tighter figure than England does. Where the insulation duty is triggered on a Deeside roof, that can mean a little more work than the same job would need across the border.

The practical consequence is small but real: on a Deeside slate re-roof, the insulation line in the quotation deserves a proper answer rather than a passing mention. Ask how the standard is being met and where the insulation is going.

Then the Thing That Actually Sets a Slate Price

How many pieces the roof takes.

A large concrete interlocking tile covers a substantial area in one piece and is single-lapped. A slate is much smaller and double-lapped, so each course overlaps the two below it. The consequence is that a slated roof takes several times as many units per square metre, and every one is lifted, positioned and nailed by hand.

That is the cost gap between slate and tile, and it is a labour gap more than a materials one.

What changes the piece count

• Slate size. A larger slate covers more area per unit, so fewer pieces and fewer nails.
• Headlap. The amount each slate overlaps the one two courses below. Increase it and each slate covers less exposed area, so the roof needs more of them.
• Pitch and exposure. Both drive the headlap. The lower the pitch, the greater the lap; a more exposed site needs more lap independently of pitch.

Which is why it is worth asking what slate size and what headlap a quotation is based on. Reducing the lap lowers the slate count and makes a quotation look cheaper for a reason you would not accept if it were spelled out.

Which Slate

“Natural slate” is a category rather than a specification, and the range of quality within it is wide. BS EN 12326-1 requires producers to declare performance in three tests, and grade 1 is the best in each:

• W — water absorption. W1 is at or below 0.6%; W2 is above it and must pass a freeze/thaw test to be usable at all.
• T — behaviour under thermal cycling, which is really about how the metallic inclusions in the stone oxidise. T1 shows no structural change and no runs of discolouration.
• S — resistance to sulphur dioxide. S1 is unaffected by strong exposure.

Ask which slate is being quoted, by producer and product name, and ask for its declaration of performance. It is a manufacturer's document that the roofer obtains from the supplier, and a contractor who can answer straight away is telling you something about how they buy materials.

And the Option Worth Pricing Alongside

Slate outlasts the nails holding it on by a wide margin. The commonest reason a slate roof needs work is not the slate — it is that every fixing went in at the same time and they have corroded together.

Where that is what has happened and the slates are still sound, the roof can be stripped, the battens, underlay, fixings and lead all renewed, and the original slates relaid. Everything is handled twice so it is not cheap, but against a full roof of new slate it frequently comes out ahead — and the building looks exactly as it did.

The Regulations in Wales, in Brief

Deeside is in Wales, and the position is not the same as it is across the border. Planning: section 55 of the Town and Country Planning Act 1990 applies in Wales as well as England, so a like-for-like re-roof is not development at all and needs no permission. But Wales never adopted the 2015 permitted development order that applies in England — it still uses the General Permitted Development Order 1995, as amended.

Building regulations: regulation 23 of the Building Regulations 2010 applies in England and Wales alike. Where more than 50% of the roof's surface area is renewed, or the work forms part of a major renovation, the roof must be brought up to current thermal standards so far as that is technically, functionally and economically feasible. A patch repair does not trigger it, and neither does a roof over unheated space such as a detached garage.

More New Roof Advice for Deeside

New roof installations in Deeside →
All new roof guides →
New Roof Installations Chester →