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MAT Limited

Also seen as: MAT, Matt de Garis Architecture
mat.gg

Architectural Technology practice led by Matt de Garis, Chartered Architectural Technologist, 25+ years' experience. Full-service from concept to completion. Not RICS-regulated. 44 applications as agent 2022-2025.

Discover innovative and high-quality architectural designs by Matt de Garis, a trusted architect with over 20 years of experience in the industry. Offering personalised, comprehensive services in Guernsey and beyond.

MAT Limited’s own words, from mat.gg . Quoted as published — this site neither vets nor endorses any firm.

Images published by MAT Limited on their own website.

What they specialise in

Work types this firm files more often than the island does — "×3.9" means nearly four times the rate that type appears across all Guernsey applications. Ordered by the value of the work, not the ratio, so the jobs that actually pay come first: a rebuild at ×1.7 is worth far more than window replacement at ×2.5.

Work typeVs island rateJobsTypical jobEst. value of this work
Single-storey extension×1.818£100,000£1,800,000
Loft conversion×3.03£60,000£180,000

"Est. value of this work" is the typical job cost for that type multiplied by how many they filed — a rough sense of where the practice's money sits, not their fees or their turnover. Needs at least 12 applications on file and 3 in the category before a ratio is shown, so a small practice can't look like a specialist on two lucky jobs. Classified from each application's own wording, so a minority will sit in a category a human would read differently.

The properties they work on

Of 44 applications this firm filed, 18 are tied to a later recorded sale of the same address, and 15 of those carry a real price. The midpoint is £774,733, each carried forward to 2026 money at the island index. Most of their filed work is in Vale (12), St Sampson (9), St Peter Port (7).

2 matched sales recorded at a nominal £1–£100 were excluded — those are family or trust transfers, not market prices. Matching is by address and parish against the States register, not a shared ID, so a shared house name can mismatch. It tells you the value bracket this firm operates in; it is not their fee and not a claim about any individual job.

Work-type mix

Classified from each application's own description text, most common first — the same keyword model this site's planning cost estimates use. Select a type to filter the applications below.

Typical cost of work

£37,906–£66,438 average, estimated per application from its own description text using this site's planning cost model — a rough guide only, not a quote from MAT Limited or a reflection of what any specific job actually cost, and it does not include design fees. Each row below also carries an estimate at the prices of the year it was filed, deflated with the island house-price index — a proxy, since that index tracks house prices rather than construction costs and the two genuinely diverge (materials spiked in 2021–22 well beyond house-price growth). No Guernsey construction-cost index is published, so this is the best basis available, and it is an estimate on top of an estimate. 4 demolish-and-rebuild applications excluded from the average — that category prices per m² of the rebuild, which isn't recorded per application here.

44 planning applications as agent — real cross-references

Success rate on decided applications: 91% granted (40 granted, 4 refused, of 44 decided — pending/withdrawn excluded)

ApplicationAddressDescriptionDecision
FULL/2023/1459Thie Veg Les Osmonds Lane La Route Des Capelles St. Sampson Guernsey GY2 4GGDemolish extensions, erect porch to north-west (front) elevation, erect single storey extensions to south-east…
Est. £52,830–£88,050 at 2023 prices
GrantedFull record
Decision notice (PDF)
FULL/2023/1570Blanchelande College Les Vauxbelets College Complex Bouillon Road St. Andrew GuernseyCreate additional gated vehicle and pedestrian access to east boundary.
Est. £5,870–£17,610 at 2023 prices
GrantedFull record
Decision notice (PDF)
FULL/2023/1600Helston Rue Cauchez St. Martin Guernsey GY4 6PQDemolish extensions, erect two-storey and single storey extension to east (rear) elevation.
Est. £52,830–£88,050 at 2023 prices
GrantedFull record
Decision notice (PDF)
FULL/2023/1714Mill House Ville Au Roi St. Peter Port Guernsey GY1 1NXErect 2 storey extension and raised terrace area to east (rear) elevation, single storey extension to south (s…
Est. £52,830–£88,050 at 2023 prices
GrantedFull record
Decision notice (PDF)
FULL/2023/1753Dualla House Rohais St. Peter Port Guernsey GY1 1FEInstall dormer to south (front) elevation and window to east (side) elevation.
Est. £52,830–£76,310 at 2023 prices
GrantedFull record
Decision notice (PDF)
FULL/2023/1754Firkin La Maison au Compte Vale Guernsey GY3 5HEExtend and alter to west (side) elevation.
Est. £17,610–£46,960 at 2023 prices
Granted
Later sold 2017-08-31 · £494,000
Full record
Decision notice (PDF)
FULL/2023/2117The Knoll Rohais De Haut St. Andrew Guernsey GY6 8SSErect summerhouse, hard surfacing and sunken seating area to east of property (Retrospective).
Est. £9,392–£21,132 at 2023 prices
Granted
Later sold 2000-12-12 · £370,000
Full record
Decision notice (PDF)
FULL/2023/2189Silver Bears Route De La Mare De Carteret Castel Guernsey GY5 7XDErect single storey extension to south elevation, erect summer house to north boundary, widen vehicle access a…
Est. £52,830–£88,050 at 2023 prices
Granted
Later sold 2025-10-09 · £1,118,812
Full record
Decision notice (PDF)
FULL/2023/2216Donkey Divers Route De L'Ancresse Vale GuernseyConvert and alter commercial premises to create 2 dwellings with associated works and erect wall to west (road…
Est. £5,870–£17,610 at 2023 prices
GrantedFull record
Decision notice (PDF)
FULL/2024/01154 Bardolino The Laurels Rue Du Pont Vaillant Vale Guernsey GY6 8BXErect an extension at 1st floor level to north-west (side) elevation.
Est. £54,863–£91,438 at 2024 prices
GrantedFull record
Decision notice (PDF)
FULL/2024/0143Crowndale La Grande Rue Vale Guernsey GY3 5HJDemolish existing outbuildings, erect single storey outbuilding/garage to south-east boundary.
Est. £30,479–£54,863 at 2024 prices
Granted
Later sold 2018-06-12 · £618,150
Full record
Decision notice (PDF)
FULL/2024/0150Glenfield Rue Du Videcocq St. Pierre Du Bois Guernsey GY7 9APVariation to previously approved plans to demolish chimney, erect single storey flat roof extension to south (…
Est. £54,863–£91,438 at 2024 prices
GrantedFull record
Decision notice (PDF)
FULL/2024/02476B Lower Vauvert St. Peter Port Guernsey GY1 1LZRemove window and install garage doors to create vehicle access to north-east (front) elevation.
Est. £30,479–£54,863 at 2024 prices
Refused
Later sold 2021-04-01 · £234,000
Full record
Decision notice (PDF)
FULL/2024/0296El Cuenta Stanley Road St. Peter Port Guernsey GY1 1QWErect single storey extension to rear and alterations to fenestration.
Est. £54,863–£91,438 at 2024 prices
Granted
Later sold 2026-02-17
Full record
Decision notice (PDF)
FULL/2024/0435Le Verbelle Damouettes Lane St. Peter Port Guernsey GY1 1ZTAlter ground levels and erect retaining wall to alter parking and widen vehicle access.
Est. £6,096–£18,288 at 2024 prices
GrantedFull record
Decision notice (PDF)
FULL/2024/0456Demie Shard Rue De La Mare St. Sampson Guernsey GY2 4PGDemolish dwelling and garage and erect 6 dwellings and associated works, alterations to roadside boundary to a…Granted
Later sold 2020-11-03 · £1
Full record
Decision notice (PDF)
FULL/2024/0458Blanchelande College Les Vauxbelets Bouillon Road St. Andrew Guernsey GY3 5AUChange of use of 1st floor and section of ground floor from retail (Use Class 10) to Education purposes (Use C…
Est. £6,096–£18,288 at 2024 prices
GrantedFull record
Decision notice (PDF)
FULL/2024/0462Blanchelande College Les Vauxbelets College Complex Le Bouillon St. Andrew GuernseyVariations to plans previously approved to create additional gated vehicle and pedestrian access to east bound…
Est. £6,096–£18,288 at 2024 prices
GrantedFull record
Decision notice (PDF)
FULL/2024/0765Plot at Lucerne Les Petites Mielles St. Sampson Guernsey GY2 4RUErect single storey detached outbuilding/garage to north east boundary.
Est. £30,479–£54,863 at 2024 prices
GrantedFull record
Decision notice (PDF)
FULL/2024/0842New Haven Sandy Hook St. Sampson Guernsey GY2 4HEDemolish chimney, erect single storey extension to east (rear) elevation, alterations to fenestration. Erect f…
Est. £54,863–£91,438 at 2024 prices
Granted
Later sold 2024-03-05 · £396,000
Full record
Decision notice (PDF)
FULL/2024/1074Le Petit Fregondee Ruette Des Saumarez Castel Guernsey GY5 7TJErect single storey garden room/store and pool to north of property.
Est. £9,753–£21,945 at 2024 prices
GrantedFull record
Decision notice (PDF)
FULL/2024/1181Sunningdale Landes du Marche Vale Guernsey GY6 8DFDemolish extension, erect single storey extension to north-east (side) elevation to create dower unit.
Est. £54,863–£91,438 at 2024 prices
Granted
Later sold 2024-05-28 · £731,250
Full record
Decision notice (PDF)
FULL/2024/1382Les Vieux Mielles Les Mielles Road Vale Guernsey GY3 5AUDemolish section of existing outbuilding and alterations to fenestration, erect external steps and associated …
Est. £30,479–£54,863 at 2024 prices
Granted
Later sold 2019-06-06 · £1,365,000
Full record
Decision notice (PDF)
FULL/2024/1383Au Milieu Croute Becrel Vale Guernsey GY3 5HYDemolish outbuilding, erect single storey extension to north-west elevation.
Est. £54,863–£91,438 at 2024 prices
Granted
Later sold 2013-06-06 · £584,250
Full record
Decision notice (PDF)
FULL/2024/1632Donkey Divers Route De L'Ancresse Vale Guernsey GY3 5SJDemolish building and erect 2 dwellings with associated works.GrantedFull record
Decision notice (PDF)
FULL/2024/1647Maison de Famille Rue de la Rocquette Castel Guernsey GY5 7AXErect single storey extension to south-east (rear) elevation, demolish/alter section of extension, install win…
Est. £54,863–£91,438 at 2024 prices
Granted
Later sold 2020-08-27 · £485,000
Full record
Decision notice (PDF)
FULL/2024/1831Aimee House Rohais St. Peter Port Guernsey GY1 1YLErect single storey extension to north (rear) elevation of main building and erect single storey extension to …
Est. £54,863–£91,438 at 2024 prices
Granted
Later sold 2024-02-27 · £755,625
Full record
Decision notice (PDF)
FULL/2024/1880Le Val Route Des Blicqs St. Andrew Guernsey GY6 8YDErect 3 storey extension, alter roof covering, install cladding and alterations to fenestration to existing ex…
Est. £54,863–£91,438 at 2024 prices
RefusedFull record
Decision notice (PDF)
FULL/2024/1881Silver Bears Route De La Mare De Carteret Castel Guernsey GY5 7XDErect single storey extension to east (side) and south (front) elevations.
Est. £54,863–£91,438 at 2024 prices
Granted
Later sold 2025-10-09 · £1,118,812
Full record
Decision notice (PDF)
FULL/2024/1988Les Marais Ruette Du Val De Haut St. Pierre Du Bois Guernsey GY7 9LBSubdivide, extend and alter existing dwelling to create 3 dwellings and associated works (Protected Building).
Est. £18,288–£48,767 at 2024 prices
RefusedFull record
Decision notice (PDF)
FULL/2024/2008Au Sommet Green Lanes St. Peter Port Guernsey GY1 1TNErect single storey extension to east (side) and north (front) with raised terrace area to front elevation and…
Est. £54,863–£91,438 at 2024 prices
GrantedFull record
Decision notice (PDF)
FULL/2024/2051Latgale 1 Helston Estate Rue De La Perruque Castel Guernsey GY5 7NXAlterations to fenestration of main dwelling. Erect single storey outbuilding, relocate oil tank and existing …
Est. £30,479–£54,863 at 2024 prices
GrantedFull record
Decision notice (PDF)
FULL/2025/0047Land at Rue Des Monts St. Sampson GuernseyErect 2 dwellings with associated landscaping and parking. (Revised scheme).
Est. £18,898–£50,394 at 2025 prices
RefusedFull record
Decision notice (PDF)
FULL/2025/0051Mancot Les Sept Etoiles La Moye Vale Guernsey GY3 5BUInstall dormer window to west elevation.
Est. £56,694–£81,891 at 2025 prices
GrantedFull record
Decision notice (PDF)
FULL/2025/01172 Bel Air Clos Victoria Avenue St. Sampson Guernsey GY2 4AXRemove section of wall and erect pillars to south boundary to create parking area and erect wall to east bound…
Est. £6,299–£18,898 at 2025 prices
GrantedFull record
Decision notice (PDF)
FULL/2025/0213Nouvelle Vie 6 Les Rouvets De Bas Perelle Road St. Saviour Guernsey GY7 9QEPartially demolish conservatory, erect single storey extension to west (rear) elevation, install cladding and …
Est. £56,694–£94,489 at 2025 prices
GrantedFull record
Decision notice (PDF)
FULL/2025/0218Mayrhofen 2 Victoria Terrace Church Road St. Sampsons Guernsey GY2 4LLErect dormer window to north-west (rear) elevation, install rooflight to south-east (front) elevation and alte…
Est. £56,694–£81,891 at 2025 prices
GrantedFull record
Decision notice (PDF)
FULL/2025/0241Demie Shard Rue De La Mare St. Sampson Guernsey GY2 4PGVariations to previously approved plans (FULL/2024/0456) to Demolish dwelling and garage and erect 6 dwellings…Granted
Later sold 2020-11-03 · £1
Full record
Decision notice (PDF)
FULL/2025/0259Blanchelande College Les Vauxbelets College Complex, Le Bouillon St. Andrew Guernsey GY3 5AUAlter roof structure and alterations to fenestration to existing pavilion and erect 3 covered gazebos to north…
Est. £15,118–£31,496 at 2025 prices
GrantedFull record
Decision notice (PDF)
FULL/2025/0280Marwin Les Dicqs Vale Guernsey GY6 8JWDemolish outbuilding, erect single storey outbuilding/garage to north-west boundary.
Est. £31,496–£56,694 at 2025 prices
Granted
Later sold 2023-11-30 · £540,000
Full record
Decision notice (PDF)
FULL/2025/0349Les Vieux Mielles Les Mielles Road Vale Guernsey GY3 5AUDemolish conservatory, erect single storey extension and alteration to fenestration to south (rear) elevation …
Est. £56,694–£94,489 at 2025 prices
Granted
Later sold 2019-06-06 · £1,365,000
Full record
Decision notice (PDF)
FULL/2025/0385Woolacombe Route Des Laurens Torteval Guernsey GY8 0RAErect single storey extension to south (rear) elevation, erect porch to north (front) elevation and alteration…Granted
Later sold 2025-01-07 · £520,000
Full record
Decision notice (PDF)
FULL/2025/0417Storage Shed Site Houmtel Lane Vale Guernsey GY3 5LGConvert building to create dwelling, change of use of agricultural land to domestic garden (1,255sqm) and asso…
Est. £18,898–£50,394 at 2025 prices
GrantedFull record
Decision notice (PDF)
FULL/2025/0478Happy Days 12 Pre De La Fontaine Robergerie Road St. Sampson Guernsey GY2 4NQErect infill extension at 1st floor level to south (side) elevation with balcony to west (front) elevation and…
Est. £56,694–£94,489 at 2025 prices
GrantedFull record
Decision notice (PDF)
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