Choosing the right bedding mortar
To get the best performance from our manhole covers, gratings and surface boxes we recommend using the appropriate materials to install them, in particular a bedding mortar that has been specifically developed for this purpose.
A suitable mortar should ideally be non-shrink, be rapid set and have a quick strength gain. We strongly advise against using standard concretes or sand and cement mortars for this purpose.
![](https://www.manholecoversandgratings.co.uk/wp-content/uploads/2023/08/Mask-Group-10.png)
A. Mix material
![](https://www.manholecoversandgratings.co.uk/wp-content/uploads/2023/08/Image-36.png)
B. Bedding layer
![](https://www.manholecoversandgratings.co.uk/wp-content/uploads/2023/08/Image-37.png)
C. Seat casting
![](https://www.manholecoversandgratings.co.uk/wp-content/uploads/2023/08/Image-44.png)
D. Level casting
![](https://www.manholecoversandgratings.co.uk/wp-content/uploads/2023/08/Image-45.png)
E. Check gaps under flange
Ensure that there are no visible gaps under the flange and smooth bedding material with trowel both inside and outside of chamber.
![](https://www.manholecoversandgratings.co.uk/wp-content/uploads/2023/08/Image-46.png)
F. Envelope flange
Use the remaining mortar to envelope the flange paying particular attention to the corner areas. Smooth out the mortar with a trowel to ensure good bonding with the casting and to avoid any initial cracks in the bedding material.
![](https://www.manholecoversandgratings.co.uk/wp-content/uploads/2023/08/Image-47.png)
G. Backfill
Check that the bedding material has hardened and backfill with asphalt. Ensure that the asphalt is properly compacted.