Cast stone should only be fitted by suitably experienced operatives. The following general precautions should be observed.
General
During construction it is advisable to protect finished work using appropriate gauge polythene sheeting. This prevent mortar drips, mastic paint and other construction materials staining or adhering to the cast stone. Mortar in particular is very difficult to remove. Every care should be taken to prevent the contamination of stone units.
Unprotected scaffolding poles, planks etc. should not be supported by cast stone items. Protect items removed from the storage area before use. Take normal frost precautions during cold weather. Brace construction to prevent damage to freshly assembled materials. Protect the top of all work at the end of eachs days work to prevent the ingress of water contamination.
Laying
All units should be laid and adjusted to final position whilst mortar is still plastic. Mortar exuding from joints should be cut away without smearing the face units.
Bedding & Jointing
Typically, cast stone is designed to be fitted with 5-6mm joints between units. Locating holes for dowel joints (if applicable) should be completely filled with an appropriate material, such as fresh mortar. Do not leave pockets that could collect water.
During hot, dry weather, the faces should be lightly sprayed with clean water to reduce suction, otherwise a dry powdery joint may occur.
When bedding cills, it is prudent to 'end bed' only, i.e mortar is placed under the stooling and joint/s only. This allows the cills to flex slightly and reduces the chance of cracking. If the cills need to be levelled, a length of timber should be used to spread to force along the length of the cill, before tapping the cill gently into position, taking care not to damage the edges of the stone unit. Once the cill has bedded and the mortar has gone off, the void under the cill can be pointed. Failure to follow this practice may result in cills cracking across their girth.
Fixing
Due consideration to the position and type of fixing to be used should be given at the design stage, members will advise on suitable applications for the various fixing options. In many cases fixings are included as a matter of process. Ties can be purchased from us or the relevant tie manufacturer.
Cutting
Our cast stone units are designed to minimise on-site cutting. If it is unavoidable, units should be cut with a diamond tipped masonry saw. Pencil mark on a line for the intended cut. Using the diamond tipped blade, start the cut on the faced side of the stone, creating a cut/groove no deeper than 10mm.
Finish the cut from the rear/unseen face of the stone. This will help to avoid the material flaking as the blade comes out through the seen face.
Once cut, units should be brushed down to remove any dust.
Final Treatment
Brush down stone units and remove any mortar spots using a stiff, non-metallic brush.
