It can, it routinely is, and on a roof that has reached nail fatigue it is the only real answer. What people want to know is what actually happens — and whether the original slates come back.
The short answer is yes, and it is one of the commonest jobs on older property. A slate roof is a system of separate components — slates, nails, battens, underlay — and all of them can be stripped off and rebuilt.
The more useful answer is what that involves in practice, because most of the anxiety about replacing a slate roof comes from not knowing what the process looks like: whether the house is left open, what happens to the original slates, and what gets found once the covering is off.
Worth understanding, because it explains why patching stops working.
Slate itself is remarkably durable — good natural slate outlasts the people who commission it. What does not last is everything holding it on. Nails corrode, and every nail on a roof is the same age and sits in the same conditions, so they degrade at broadly the same rate and reach the end of their working lives together.
The result is slates beginning to slip in ones and twos, in unrelated places, with no storm to explain them. Once that is general there is no repair that addresses it — the slates either side of the one you refix are on the same clock.
The battens beneath, and the bitumen felt behind them, follow a similar path. That is why replacing a slate roof is a strip and rebuild rather than a re-covering: the things that failed are underneath the slates.
Erected first, usually a day or two ahead, and designed for the property. Where it stands on the public footway a licence is needed from Cheshire West and Chester Council.
This is the answer to the question everyone asks. The roof is never opened all at once. It is stripped in manageable areas, and each area is rebuilt or sheeted before the next is opened. Any open section is covered at the end of the day and whenever weather requires. You remain in the house and it remains weathertight.
As they come off, slates are assessed. Sound ones are stacked for re-use; delaminated, cracked or thin ones are discarded. On most old roofs a meaningful proportion will not be worth keeping. Reclaimed slates also need re-holing, because the original nail holes will not line up with new battens at a new gauge.
Whether re-use is worth it depends on why you are doing it. For matching appearance on period property it often is. As a way of reducing cost it usually is not, because the sorting and handling consume much of the saving.
The one opportunity anyone will get to see the roof frame properly. Rafters, purlins and wall plates are examined, with particular attention to the rafter ends where they sit on the wall plate — the commonest place for rot, because that is where a long-failing gutter deposits water.
Defective timber is replaced or spliced. This should happen at a rate agreed before work started, and you should be shown what was found before it is covered again.
New breathable underlay, correctly lapped and dressed into the gutter. New treated battens at the gauge the slate size and roof pitch require. Slates laid and nailed to specification, with the fixing pattern set by the exposure of the site. New lead to chimneys, abutments and valleys. Ridge and hip finished with a mechanically fixed system rather than mortar.
Eaves and ridge ventilation so air can move through the roof space, and insulation brought up to current standards where the threshold is crossed — kept clear of the ventilation path so the two do not work against each other.
Gutters cleared and tested, site cleaned, a magnetic sweep for nails, scaffold struck. Then the paperwork: a compliance certificate, a written guarantee, and any manufacturer warranty.
So that nothing is a surprise, the common discoveries once a slate roof is off:
None of these is unusual and none is a crisis. They are the reason the roof is being replaced rather than repaired.
If slate goes back on, the structure is being asked to carry what it was designed for and no structural question arises. It is also the case that raises no planning question, because a like-for-like renewal is not development at all.
Changing to something else is where the questions start. Concrete tile is heavier than natural slate, so the frame needs assessing. Most tiles need a steeper minimum pitch than slate, so the roof may not suit them. And a visible change of covering inside a conservation area is a conversation to have with the council first.
Two separate systems. Planning: a like-for-like re-roof does not materially affect the external appearance of a building, so under section 55 of the Town and Country Planning Act 1990 it is not development at all and needs no permission. A visible change of covering can be a different matter, particularly inside a conservation area, where the test is applied more tightly.
Building regulations: where more than 50% of the roof's surface area is renewed, or the work forms part of a major renovation, regulation 23 of the Building Regulations 2010 requires the roof to be brought up to current thermal standards so far as that is technically, functionally and economically feasible — 0.16 W/(m²K) for a roof in an existing dwelling. A patch repair does not trigger it, and neither does a roof over unheated space such as a detached garage.
We will tell you whether the existing slates are worth reclaiming and what the structure underneath is likely to need.
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