What Does Complete Roof Replacement Cost in Runcorn?

The cost drivers for a complete replacement are much the same anywhere, and they are set out on our Runcorn cost guide. This one is about the part that is specific to a lot of Runcorn housing and that quotations tend to reduce to a single unexplained line: the insulation.

Why It Matters More on This Stock

Runcorn's New Town housing was built between the mid-1960s and the late 1980s. The insulation standards of that period are a very long way below what is required now — and unlike windows or a boiler, roof insulation is not something most people have ever revisited.

So on a great many Runcorn roofs the original specification is still up there, compressed, gappy at the edges and laid in one direction between the joists. A complete replacement is the moment that gets fixed, because the roof is open and the access is already paid for.

The Two Routes, and How to Choose

There are two places to put insulation in a pitched roof, and the choice is not a matter of taste — it follows from what you use the loft for.

Cold roof: insulation at ceiling level

The insulation sits between and over the ceiling joists. The loft space is then outside the heated part of the house — cold in winter, as it always was — and it has to be ventilated so that moist air from the house cannot condense on the underside of the roof.

• Cheaper per square metre, and the material is simple
• The obvious answer where the loft is used for storage and nothing else
• Requires eaves ventilation that is genuinely open, not blocked by the insulation itself
• Pipework and tanks in the loft are now on the cold side and need lagging

Warm roof: insulation at rafter level

The insulation follows the slope of the roof, so the loft space is inside the heated envelope. More expensive, and the right answer in specific circumstances.

• Necessary where the loft is or will be habitable
• Sensible where there is a room in the roof already, or a dormer
• Keeps tanks and pipework on the warm side
• Loses a little headroom, which matters in a converted space
• The ventilation strategy is different, and has to be designed rather than assumed

The Part That Goes Wrong

Ventilation, and it goes wrong in a specific and avoidable way.

A cold roof works because air moves through the loft: in at the eaves, out at the ridge or at high level. That airflow carries away the moisture that inevitably finds its way up from the house. Remove it and the moisture condenses on the coldest surface it can find, which is the underside of the underlay.

The commonest cause is insulation pushed hard into the eaves, right to the point where the rafters meet the wall plate, sealing the inlet. It looks thorough. It is the reason for a great many damp lofts.

• Eaves ventilators keep the path open at the bottom regardless of how the insulation is laid
• Ridge or high-level ventilation lets the air out again — an inlet with no outlet does very little
• Breathable underlay helps, but it is not a substitute for ventilation and should not be quoted as one

Ask any quotation to state the ventilation provision explicitly, at the eaves and at high level. It is inexpensive and it is what stops a well-insulated roof becoming a damp one.

What a Complete Replacement Should Contain

The insulation sits inside a larger scope. In full:

• Existing covering, battens and underlay stripped and removed from site
• Structure inspected while exposed, with an agreed rate for defective timber
• New breathable underlay across the whole roof, dressed into the gutter
• New treated battens at the gauge the covering requires
• The covering laid to a fixing specification calculated for the address
• New lead at every junction, not only where it has already failed
• Ridge and hip mechanically fixed
• Insulation to the applicable standard, with the method stated
• Eaves and high-level ventilation, kept clear of the insulation
• Scaffolding for the duration
• Building control notification or self-certification, and a compliance certificate at the end

If a quotation says only “insulation upgraded”, ask which route, to what depth or performance, and what ventilation goes with it. Those three answers are the difference between a warmer house and a damp loft.

The Regulations, in Brief

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.

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