Repairs: flues, fireplaces and chimneys

A number of options are available. They depend very much on the individual circumstances in the property, so generalisation only is possible.

Solution 1

If the chimney is a structure built against the party wall in a semi-detached or terraced house, then with luck it should be possible to install a steel joist to pick up the load – supporting the joist in turn across internal load-bearing walls (or sometimes the front and rear main walls of the building when a substantial joist section may become necessary).

Note: you may need to put a Party Wall Award in place if the RSJ needs to rest into the party wall (thus changing its loading characteristics).

The RSJ will only sit beneath a portion of the chimney, so ensure that all the masonry is properly tied in. Also, it would be suitable to support the upper section of the chimney stack on a reinforced concrete lintel (or more, if a large chimney).

The use of stainless steel helical bars to reinforce the joints of the upper sections of the chimney may be appropriate and help prevent its sagging or distorting and ensure the load is concentrated on the steel joists.

Sometimes you can insert the RSJ running at an angle across the building if that is the only way in which load-bearing walls can be picked up (see diagram below).

If you are at all concerned that there is any significant additional load onto previously unloaded walls, check the wall's condition (the masonry bond) and the foundation bearing beneath the floors.

Certainly you need to ensure that the wall is continuous. For example, in a terraced house check that the wall has not been opened up between the lounge and dining room, changing the load path down to the ground floor.

Solution 2

The final option is to remove the chimney entirely and reinstate the roof and roof covering above if a suitable position for load-bearing components beneath cannot be located.

Chimneys on listed buildings

Total removal of a chimney may be a problem in a conservation area or with a listed building.

In these circumstances it is sometimes possible to obtain permission from the local authority to use a fibre-glass mock-up chimney to replace the masonry original.

If leaving the defective structure in situ would cause 'damage to the detriment of the character of a listed building', it should be possible to persuade the local conservation officer accordingly. If in doubt, re-read the Act in order to negotiate!

COST SEQUENCE - Taken down chimney; 2-storey dwelling

1. Supply a scaffold tower access or scaffolding and roof ladder. Dust sheets to be placed within roof void to collect all light debris and dust.
2. Reduce 4-flue brick chimney by 2m below roof/rafter height.
3. Install new rafters inside of original trimming pieces to newly inserted ridge board in line with existing ridge.
4. Allow for additional timber/plywood plating over joints to secure all connections between old and new work (ridge board) and timber joist plating, where appropriate, around trimmers to secure new inserted rafter sections. Allow for good quality shear resistant stainless steel screw fixings with minimum 3 fixings on each side of each joint; alternatively, bolt through (allow for, say, total 6 no. fixings in engineerings stuf bolt per rafter plate about M12 diameter/thread).
5. Strip back margins of tile covering and lay in new roofing felt across the void with minumum 150 mm laps across rafter joints.
6. Install new hanging battens to match existing tile or slate guage.
7. Fit new tiles (slates). Allow for stripping off rear elevation to match old tiles into the front elevation and hang new tiles on the exposed and stripped rear elevation sections.
8. Allow for cart away of all risings and clean the roof space of all debris. Strike the scaffold and clean away.

Take down chimney; 2-storey dwelling - COST £2700

Small works pricing

Since the original price estimating in 2008 the economic turmoil of the last few years has caused some disparities in pricing - if you are reviewing these figures in the London area they may look laughable - if you are located in Hull they might still look a bit expensive. Please treat them with caution and of course always consider obtaining more than one quote against which to test prices. Reference to the BCIS or a small works pricing book such as Spons or Laxton's will help assess costs and the hourly labour rates upon which they are based.