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HD Sharman Ltd.
High Peak Works,
High Peak,
Derbyshire SK23 0HW

Seamsil® 400 Bolt Encapsulation System

Problems with corrosion on metal roof fixings

Over time, bolts used to fix metal roof sheets can be at risk of corrosion, moisture and other damage from environmental factors. This can weaken the bolts, meaning they are likely to become loose and break. Using a bolt encapsulation system can be an effective way to protect bolts from damage and extend their lifespan. 

Bolt encapsulation systems are the most sustainable option for protecting bolts and improving the environmental impact of structures and equipment. By decreasing the demand for new materials and reducing maintenance requirements, these systems can help promote sustainability and reduce waste. 

Seamsil® 400 is a silicone based system engineered specifically to prevent further corrosion of roof sheet bolts and fixings by providing a temporary, protective elastic seal.

Seamsil® 400 Bolt Encapsulation System

Our new fixing nozzle system enables Seamsil® 400 bolt encapsulation system to be efficiently applied onto metal roofs. Ensuring a better encapsulation and finish and eliminating labour intensive approaches. No more bending or getting down on your knees.

  • This method is around 3x quicker than brush based methods.
  • Cover up to 50 fixings in 2 minutes.
  • Each tube contains enough Seamsil® 400 to cover 150 fixings.
  • Use as a standalone system or with the Delcote® full roof coating system.
  • Backed by a 10 or 25 year guarantee when applied as part of the Delcote® full roof coating system.
  • Or a standalone guarantee of 12 months is applied as the Seamsil® 400 bolt encapsulation system.


Independently tested against leading rigorous industry standards, the systems have been specifically designed for the gutter and roof environments. Installed into the commercial roof sector since 1985, our systems have stood the test of time, providing complete peace of mind to specifiers.

These market leading systems are underpinned by a range of guarantees to choose from.

  • Silicone systems have excellent elastic and flexible properties to withstand normal surface movement.
  • Using GE Silicone technology with its proven long life, it’s unaffected by UV or extremes of weather and temperature.
  • Seamsil silicone systems have exceptional adhesion to cleaned and prepared surfaces and cure to provide a tough, elastic seal, effectively encapsulating the damaged area to restrict further deterioration.
  • Proven track record in corrosion and degradation control.

Aside from ensuring all roof fixings and surrounding substrate are thoroughly clean and dried before the application of Seamsil® 400, you should also:

  • Check the integrity of existing fixings.
  • Suspect fixings should be replaced in line with recommended standards.
  • Non-integral plastic caps should be removed and any loose fixings tightened. 
  • Remove any degraded washers or fixing caps. 
  • Remove any previously applied coatings, especially bitumen based compounds.

Metal roof sheet with Seamsil® top coat – 

Apply one liberal coat of Seamsil® top coat by brushing over and around the roof fixings, ensuring a full encapsulation is achieved, especially at the base. Allow to fully cure.

Metal roof sheet with Seamsil® fixing grade sealant –

Place the nozzle over the fixing, ensuring it is flat and level with the roof sheet. Squeeze the trigger ensuring that the required amount of sealant dispenses to encapsulate the fixing. Allow to fully cure.


Yes, the Seamsil® Sealant is gun applied around the whole of the fixing, forming a complete bridged seal especially at the base. Please see the Product Specification document.