Improve warmth, comfort and energy efficiency with our range of Cavity & Internal Wall Insulation, ideal for new builds, extensions and renovation projects. Wall insulation plays a key role in reducing heat loss and helping maintain a more consistent indoor temperature, making rooms more comfortable while supporting lower heating costs. Whether you’re insulating a cavity wall during construction or upgrading internal walls as part of a refurbishment, choosing the right insulation helps deliver long-lasting performance.
Cavity insulation is designed to fit between wall layers to reduce heat transfer and improve overall building efficiency. Internal wall insulation is ideal for stud walls, partition walls and lining systems, offering thermal improvement and, in many cases, added sound reduction between rooms. These products are widely used across domestic and commercial projects where better insulation and building performance are required.
For best results, select insulation suitable for the wall type and thickness, ensure boards or rolls fit snugly without gaps, and follow recommended guidance on vapour control and ventilation. Using compatible membranes and sealing products can also help improve results by reducing drafts and maintaining a clean install.
Shop online today for cavity and internal wall insulation with delivery and collection available.
The Knauf 100 mm DriTherm Cavity Slab 32 (3.28 m²) is a high-performance full-fill cavity wall insulation slab engineered to deliver excellent thermal efficiency with a low lambda value of 0.032 W/mK.…
The 100 mm DriTherm Cavity Slab 37 (6.55 m²) is a high-quality full-fill cavity wall insulation slab designed to provide reliable thermal performance in masonry construction.…
The Knauf 125 mm DriTherm Cavity Slab 32 (2.18 m²) is a high-performance full-fill cavity wall insulation slab designed to deliver excellent thermal efficiency with a low lambda value of 0.032 W/mK.…
The Knauf 150 mm DriTherm Cavity Slab 32 (2.18 m²) is a high-performance full-fill cavity wall insulation solution, engineered to deliver excellent thermal efficiency with a low lambda value of 0.032 W/mK.…
The Knauf 50 mm DriTherm Cavity Slab 37 (6.55 m²) is a high-quality full-fill cavity wall insulation solution designed to provide effective thermal performance in masonry construction.…
The Knauf 75 mm DriTherm Cavity Slab 32 (3.28 m²) is a high-performance full-fill cavity wall insulation slab designed to deliver excellent thermal efficiency with a low lambda value of 0.032 W/mK.…
The 75 mm DriTherm Cavity Slab 37 (4.37 m²) is a high-quality full-fill cavity wall insulation slab designed to deliver dependable thermal performance in masonry construction.…
The Knauf 50 mm Acoustic Roll (16.2 m²) is a high-performance glass mineral wool insulation roll designed to deliver effective acoustic sound absorption in internal walls, partitions, floors and ceilings.…
The SuperQuilt 1.2 m x 10 m Multifoil Insulation (12 m² per roll) is a high-performance reflective insulation blanket designed to provide effective thermal insulation in roofs, walls and floors.…
Builders merchant depots across Leicestershire and Rutland
Three William Hercock depots in Melton Mowbray, Leicester and Oakham supply trade professionals and DIY customers with building materials, timber and landscaping supplies.
Collect from your nearest yard or have it delivered straight to site with HIAB and Moffett offload.
Trade and publicEvery depot is open to trade professionals and DIY customers
Collect or deliveredCollection from any branch or local delivery
HIAB and MoffettCrane and forklift offload straight to site
Rated up to 4.8★ on GoogleFrom 160+ customer reviews across our three depots
Opening hours
The same at all three depots
Monday – Friday7:30am – 5:00pm
Saturday8:00am – 12:00pm
SundayClosed
Bank holiday hours may differ. Please call your branch to check.
What every depot offers
Whichever branch is closest, you get the same service.
Bulk bags and pallet quantitiesOrder by the bag, the bulk bag or the full pallet.
Fast local delivery with HIAB and MoffettCrane and truck-mounted forklift offload, straight to site.
Trade accounts with credit facilitiesCredit terms and trade pricing. Open a trade account
Expert advice from an experienced teamHelp choosing materials and working out quantities.
Reliable stock availabilityKey product ranges kept in stock at every branch.
Open to trade and publicBuilders, contractors and DIY customers all welcome.
Need help with your project?
Our depot teams can help you choose materials and work out quantities.