Installing a Vented Fireplace

Unless you’re installing an electric fire, any fire you install into a property will need to be vented. Whilst installing a vented fireplace into a property with an existing and functioning chimney can be relatively quickly achieved. Even if you have no chimney at all you can still install a vented fireplace for a gas fire by using a balanced or powered flue. It is also possible to install gas fires that don’t even require a flue.

However, these are only suitable for use in large rooms and require the waste gases from the combustion process to be ‘scrubbed’ by a catalytic converter. The minimum specifications for the type of flue system you require will be specified by the fire manufacturer. The following describes how to install a vented fireplace into a property with an existing chimney.

Fireplace Options

A new or replacement fireplace can be made from a variety of materials, but most the most commonly used materials are stone and wood. When choosing your new fireplace you should check that it is suitable for use with a working fire, of the type that you have bought or use.

Be especially careful that you don’t buy one that is purely for decorative purposes, as it is unlikely to be heat resistant. Check your local building regulations as you may well need to have a hearth conforming to a minimum specification, even if you’re eventually going to fit a gas fire.

Installing a Marble Hearth with a Wooden Surround Fireplace

The first thing to do is install the hearth. If the floor is particularly un-level, apply a leveling compound first; after getting the floor reasonably level spread a thin layer of white mortar to act as a bed for the hearth to sit on.

Position the hearth on the white mortar checking that it is centrally positioned to the inner, or constructional, hearth and is level - along its length, width and diagonals.

Don’t struggle with a large marble hearth - get help lifting and positioning it, rather than risk an injury or damaging the hearth!

Apply white mortar to the wooden upright legs using an adhesive spreader to get a good surface texture to aid adhesion. Use a long spirit level to get the legs into a vertical position; any mortar escaping onto the walls will probably be covered by the upright surrounds, but any mortar spilling onto the marble hearth should be removed immediately with a damp cloth.

Allow the mortar to dry and harden. Then, spread white mortar on the top panel and position it on to the wall above; rest it on the upright legs and check it is level before pressing it on to the wall - re-check that it is horizontal.

Position the upright surrounds and the mantel shelf so that you can mark the fixing points for the brackets. Remove the surrounds and drill pilot holes for the screws, insert plugs into the holes then re-position the upright surrounds and the mantle shelf and secure them into place. Any gaps can be filled with the white mortar.

Installing a Stone Hearth and Surround Fireplace

On the floor mark out the exact dimensions and position for the hearth, then lay a 1/4 inch bed of slab mortar; use your trowel to create an uneven surface to ensure a good adhesive surface for the slabs. Position the slabs on to the mortar, constantly checking that they are level and then leave the mortar to dry.

Once the mortar is dried the slabs can be pointed with matching or contrasting mortar according to your overall room design. When the pointing has dried you can start to fit the upright legs. With the help of a spirit level, position a section of upright on the hearth and mark the fixing points for the brackets on the wall and upright.

Remove the upright, drill pilot holes and insert plugs. Screw a bracket to an upright then re-position it having laid a thin layer of mortar on the hearth for it to sit on - use mortar that is the same color as that used for pointing the hearth - then securely screw the bracket onto the wall.

Repeat this process for the other upright; then use a long spirit level across both of the uprights to make sure the mantle shelf will sit ‘level’. The mantle shelf will sit on a thin layer of mortar placed on top of the uprights. It can be secured to the wall by brackets fixed to the top of it - or by using a ‘hidden’ bolt mechanism.

Whichever system is in use with your mantle shelf; position the shelf and mark where the fixing points are needed, drill pilot holes and fit plugs or the bolt sheaths. Spread a thin layer of mortar on top of the uprights, re-position the mantle shelf, check that it is level and secure it to the wall. NB. Don’t struggle with a large and heavy mantle shelf - get help lifting and positioning it, rather than risk an injury or damaging the shelf!