St Austell rarely makes the postcards, which suits its homeowners fine. The clay industry built the town in granite and killas, the postwar decades wrapped it in family estates, and today its average house costs less than almost anywhere else we cover - so a well-judged conversion changes what a family can do here more than a far bigger budget changes things on the coast.
We convert lofts and garages from Trewoon to Carlyon Bay, and we carry the two specialisms this town actually requires: engineering steels onto rubble stone walls that predate every modern code, and steering roof work through the World Heritage Site rules that cover Charlestown. Survey, structural design, Cornwall Council building control and fit-out - one team, one written quote with the VAT already in it.
Tell us what you are thinking and we will come and look at it. No charge, and no obligation to go ahead.
Half an hour, no charge, and a straight answer on whether the space works.
Steels, floors and bearings are our own work, not a subcontractor's problem.
Full Plans submitted to Cornwall Council, completion certificate at the end.
Same people from first survey to final walk-round. Nobody to chase.
For two and a half centuries the ground north of St Austell has been dug for china clay, and the town is the industry's dividend: terraces at Mount Charles and Bethel raised in the clay boom, a Georgian export harbour at Charlestown built to ship the stuff, and the white "Cornish Alps" of spoil still standing on the skyline. Even the walls are geology - granite rubble and killas from the same ground the kaolin came out of.
Modern St Austell spreads well beyond the clay-boom core, through estate neighbourhoods at Sandy Hill, Boscoppa and Holmbush out to Carlyon Bay's cliff-top avenues. With nearly 24,400 residents it has quietly become Cornwall's biggest town - bigger than the city up the road - while staying one of its most affordable. That combination, lots of families and gentle prices, is exactly the territory where loft and garage conversions do their best work, and it is why we spend so much of our week on this side of the patch.
Terrace, semi or harbour cottage - the service is chosen by the house, and this town has every kind of house.
From steep clay-boom terrace roofs at Mount Charles to wide postwar semis at Boscoppa, St Austell lofts come in every flavour - including the Charlestown kind, where World Heritage rules make conservation rooflights the smart route. We match the method to the street.
Learn more about loft conversions in Cornwall
In Cornwall's most affordable big town, the garage conversion is king: a modest spend that adds a whole room to houses where every extra square metre counts. The estates at Sandy Hill, Holmbush and Boscoppa are full of garages waiting for a better job.
Learn more about garage conversions in Cornwall
St Austell's prices make it one of the few Cornish towns where three generations can realistically share one address by choice rather than necessity. An annexe formalises it properly - with the council tax and VAT questions answered before work starts.
Learn more about annexes & granny flats in Cornwall
Strip away the postcard towns and this is where Cornish family life actually happens at scale. Five reasons the conversion case is strongest here.
Nearly 24,400 people - more than Truro - at an average around £242,000. Nowhere else we work does a modest conversion budget move the needle on a house this far, and nowhere else is the gap between 'outgrown it' and 'fixed it' so affordable to close.
The clay industry built this town twice over - it paid for the terraces and it supplied their granite and killas walls. Those walls reward builders who understand them and punish ones who guess. We put the engineering where the guesswork usually goes.
The twentieth century gave St Austell whole neighbourhoods of straightforward semis and bungalows with garages attached - Sandy Hill, Boscoppa, Holmbush, Trewoon. For conversion work this is prime material: predictable structure, clear planning, quick programmes.
The town average hides its coastal fringe, where Georgian harbour cottages and cliff-top homes trade far higher. Conversions there carry heritage rules and reward heritage care - and the value they add per square metre is the best in the PL25 postcode.
Lottery-funded restoration has rebuilt the historic shopfronts and the 1844 Market House, and regeneration money keeps arriving. Improving rather than leaving is the whole civic mood here - a conversion is the household-scale version of it.
St Austell sends us more garage conversion enquiries than loft ones - the only large town in our patch where that is true, and the house prices explain it perfectly.
One sequence for the whole town - though stage one works hardest on the older stone houses, and stage three works hardest within sight of Charlestown harbour.
We measure the head height from the top of the ceiling joist to the underside of the ridge, look at how the roof is built, and work out where a staircase can physically land. On a garage we check the floor level, the damp course and how the walls were built. This is the visit that decides whether the job is worth doing at all, and we would rather tell you no at this stage than three weeks in.
One document, VAT included, with the structural allowance shown as its own line rather than buried. Where a wall has to be opened up before anyone can be certain what the steel is bearing onto, we say so and give you the range. Exclusions are listed. If your quote from someone else has no structural line on it, that cost has not gone away.
We check whether your permitted development rights survive. Dormers are not permitted development on article 2(3) land, which in Cornwall means every conservation area, the National Landscape and all ten areas of the Mining World Heritage Site. Rooflights usually still are. Getting this right at the start is the difference between a four-week start and a four-month one.
Architectural drawings, then a structural engineer sizes the beams and specifies the bearings. We submit Full Plans to Cornwall Council rather than a Building Notice - it costs less in every fee band and it means the details are agreed before anyone cuts anything, instead of being argued about on site.
Scaffold where the work needs it, then the load-bearing stage: new floor joists sized for a habitable floor rather than a storage loft, steels in, padstones and spreaders bedded properly. On older Cornish stone walls this is where surprises live, which is why it happens early and why we look before we price.
Roof made good, dormer or rooflights in, windows glazed. Once the space is dry it is insulation, electrics, plumbing and the stair. Insulation is worth paying attention to here - the limits for a conversion are tighter than for a new-build house, 0.15 on the roof against 0.16, which catches a lot of people out.
Skim, decorate, doors, sockets, flooring. Then the building control final inspection and your completion certificate, the electrical certificate, and the written structural warranty. We walk the room with you before we take the scaffold down, not after.
The clay country's houses were built by people who expected them to last centuries, and plenty have. Work added to them should hold itself to the same standard - ours does, in writing, for ten years from handover.
The warranty covers the part we control: the structure. Beams sized and signed off by an engineer, bearings that are capable of taking the load, floors that meet their span, and a roof that stays weathertight where we have opened it up. It is written down and handed over with the building control completion certificate at the end of the job, not promised verbally on the doorstep at the start of it.
It matters more here than it would upcountry. A lot of Cornish walls are random rubble stone rather than cavity brickwork, and Eurocode 6, the masonry design standard, explicitly does not cover rubble masonry. There is no code route for dropping a steel onto a wall like that. It has to be justified by an engineer from first principles, which is exactly why we open up and look before we price, rather than after.
The town keeps three of Cornwall's heavyweight attractions within a few minutes' drive.
The world-famous biomes rise out of a former clay pit at Bodelva, just outside town - a covered rainforest and a Mediterranean world under vast honeycomb domes, plus gardens, concerts and the long zip wire over the lot.
Learn more about Eden Project (opens Google Maps in a new tab)
A Georgian harbour built between 1791 and 1801 to ship copper and clay, now a World Heritage Site setting lined with tall ships and film crews - Poldark shot here for years. The Shipwreck Treasure Museum sits above the dock.
Learn more about Charlestown (opens Google Maps in a new tab) The UK's only china clay museum, set in two former working pits just north of town - the story of the industry that built St Austell, complete with a viewing platform over a vast modern pit still being worked next door.
Learn more about Wheal Martyn Clay Works (opens Google Maps in a new tab)Conversions across mid and north Cornwall, from Victorian terraces in Truro to bungalows on the coast road.
We had been told twice that our roof pitch was too shallow for a loft. The survey here came back the same, but with an actual option - a rear dormer to buy back the headroom over the stair. They measured 1.9m at the centre of the flight and showed us where that sat against the regs before we spent anything. Two bedrooms and a shower room now.
Ours is an old miner's terrace and the walls are random rubble, not cavity. They were straight with us that the steel bearings would need opening up before anyone could price it properly, and they got the engineer out first rather than guessing. Cost more than a modern semi would have, but nothing on the quote changed from start to finish.
We're inside the mining World Heritage Site so a dormer was never going to fly. They knew that on the first visit and steered us to conservation rooflights instead, which kept us out of a planning application altogether. The slate was matched properly too - you cannot tell where the new work stops.
Integral garage into a snug and a utility. What sold me was that they explained the floor build-up - the damp membrane, the insulation, why the finished floor ends up a couple of inches higher than the hall. Every other quote just said 'convert garage'. Warm room, no condensation, and it was done in under four weeks.
Terraced house on a hill, so the scaffold had to go on the pavement. They sorted the licence with Cornwall Council and gave us the two-week lead time up front instead of turning up and discovering it. Small thing but it tells you how the rest of the job went.
A proper annexe for my mum, and honest advice on the bits I would never have thought about - that the council tax discount depends on who lives there, and that a planning condition tying it to the main house would knock out the reduced VAT rate. They flagged it before we committed rather than after.
Garage conversions from roughly £15,000, rooflight lofts from £30,000, dormer and hip to gable work from £45,000, all before VAT - with older stone houses carrying a structural allowance we show as its own line rather than burying. On this town's prices the garage is often the smartest first move, and the free site visit will tell you honestly whether that is true of yours.
St Austell anchors the south-eastern side of our working circle. Wherever you are on this list, the crew, the quote format and the warranty are the same ones.
Whether it is a clay-boom terrace, an estate semi or a cottage above Charlestown harbour, the free visit gives you the same three things: what is possible, what the rules say for your street, and a fixed written price for doing it properly.
