TV Mounting on Thermalite Aerated Blocks¶

Thermalite aerated concrete blocks are soft lightweight blocks common in UK modern homes requiring specialist fixings for TV mounting. This guide covers block identification, correct fixing selection, and safe mounting practices.

Identifying Thermalite Blocks and Fixing Requirements¶

Thermalite aerated blocks (also called Aircrete or Hebel) are lightweight concrete blocks used in UK new-build homes since the 1990s. They are 30-50% lighter than dense concrete blocks with lower compressive strength (2.9-7.3 N/mm2 vs 7-25 N/mm2 for dense blocks). Identify by drilling a test hole - Thermalite produces a fine powdery dust rather than granular rubble. The block colour is pale grey with a soft crumbly texture. Standard wall plugs provided with TV mounts do NOT work in Thermalite - they spin and fail to grip. Specialist fixings required: Thermalite-specific wall plugs with deep spiral or finned designs that compress and grip the soft block. Fischer FID 50 (10x50mm, £8 pack of 20) is the best Thermalite fixing for TV mounting. Resin anchors also work for Thermalite - inject two-part polyester resin into a 12mm hole and insert a threaded stud. For TVs over 25kg use resin anchors for maximum security. Maximum pull-out force for Fischer FID 50 in Thermalite is approximately 300kg per fixing - easily sufficient for TV mounting.

Installation Guide for Thermalite Block Walls¶

Step 1: Confirm wall construction as Thermalite by test drilling. Step 2: Select fixings - Fischer FID 50 for TVs up to 25kg, Fischer FIS VL resin anchors for heavier TVs. Step 3: Mark bracket position with TV centre at 105-115cm. Step 4: Drill pilot holes with 10mm SDS masonry bit. Dry drill only - water cooling damages Thermalite. Drill depth 55-60mm. Do not over-drill as Thermalite is soft and the bit can easily go too deep. Step 5: Clean holes - blow out dust (an essential step for Thermalite as dust prevents fixing grip). Step 6: Insert Fischer FID 50 fixings by tapping gently with a hammer until flush. Step 7: Screw in M8 bolts to expand the fixing. Step 8: Attach the wall plate and tighten all bolts to 10-15 Nm. For resin anchors: inject resin, insert M8 stud, cure 30 minutes, attach wall plate. Avoid over-tightening as Thermalite can crush under high compression. Maximum TV weight with Fischer FID 50 fixings: 35kg for four fixings. For TVs over 35kg use resin anchors.

Specifications and Comparison¶

Fixing Type	Max TV Weight	Hole Diameter	Hole Depth	UK Cost
Fischer FID 50	35kg (4 fixings)	10mm	55-60mm	£8 for 20
Fischer FIS VL Resin	60kg (4 fixings)	12mm	80mm	£25-£35 for kit

FAQ¶


: . For more information see our Concrete Wall TV Mounting Guide.

Last updated: 2026-05-31.

External Resources¶

For further information consult authority guidelines at the UK Government Building Regulations.