We choose the cap by fuel and appliance, fix it to the crown slab or the end of the liner and check that it does not hinder the flue gases or the cleaning of the chimney. In the form, give the chimney size and the connected appliance.
What a chimney cap does
- Stops rain and snow falling into the flue channel, where water wets the masonry and mixes with soot into an acidic liquid.
- Protects the crown slab and the top courses of brick from direct rain.
- Keeps out leaves and stops birds nesting in the flue channel, a common cause of blocked summer house chimneys.
- In a windy spot it reduces wind blowing down the flue channel and smoke returning into the room.
A cap does not replace the correct chimney height. If the chimney is too low in relation to the ridge, smoke can come into the room even with a cap: chimney height above the roof.
What the building code says about caps
The building code allows caps and other covers, including deflectors, to be fitted on the chimneys of local heating devices, provided they do not hinder the heating device's operation or the cleaning of the chimney. So a cap is not mandatory, but it must not narrow the outlet for flue gases, and it must be removable or allow the flue to be cleaned.
A spark arrester, or mesh in the cap, is not required for a chimney by either the fire safety regulations or the building code. Mesh keeps birds out, but on a wood stove or fireplace it quickly clogs with soot and reduces the draught, so it is used only if it can be cleaned easily.
LBN 231-15 (Cabinet Regulation No. 310 of 16.06.2015), point 65: caps and other covers, including deflectors, may be fitted on the chimneys of local heating devices if they do not hinder the heating device's operation or chimney cleaning work. Cabinet Regulation No. 238 of 19.04.2016 mentions spark arresters only for vehicles, not for chimneys. Regulations checked 04.11.2026; from 2 January 2027 they will be replaced by new fire safety regulations, which we will check as soon as they are adopted. Source: likumi.lv, checked 04.11.2026.
Which cap to choose
| Type | Suitable for | What to know |
|---|---|---|
| Simple cap on legs | most stoves, cookers and fireplaces | a large enough opening must remain between the cap and the flue channel |
| Deflector | windy spots, chimneys next to taller trees or buildings | helps against wind blowing down, but does not replace a chimney that is too low |
| Rotating cap (turbine) | less often; only after an inspection | ices up and gets sooted, then starts hindering the draught; must be removed for cleaning |
| Cap with mesh | unused flues, ventilation ducts, places with birds | on wood appliances the mesh clogs with soot and needs regular cleaning |
| Manufacturer's terminal | gas and pellet boilers with a liner | the manufacturer's instructions specify which terminal is suitable; an ordinary cap may be prohibited |
Material: stainless steel lasts longer than galvanised sheet, especially on a gas boiler, whose flue gases are moist. We choose the size by the chimney head or the liner diameter.
How we fit a chimney cap
- Measurements We measure the chimney head or the liner diameter and look at the crown slab. If the crown slab is crumbling, we do not fix a cap to it until it is repaired.
- Cleaning Before fitting the cap we clean the flue and remove any nests and leaves.
- Fixing We screw the cap to the head with anchors or fit it on the end of the liner so the wind does not tear it off.
- Check We check that the cap does not hinder the draught and that the flue can be cleaned from above.
If the head or crown slab needs restoring at the same time: chimney head rebuilding. If the cap is wanted because the chimney is damp, we first check whether the damp is condensation: condensation in the chimney.
How much does chimney cap installation cost?
The price depends on the cap type, material and size, the height of the chimney and access to the roof, the condition of the crown slab and whether we clean the flue or repair the head on the same visit. Materials are priced separately from the labour. The specialist will name the price after you submit the form, before the work. Other prices: prices.
Sources
- Caps and other covers, including deflectors, may be fitted on chimneys if they do not hinder the appliance's operation or cleaning (LBN 231-15, 65) checked 4 November 2026
- Cabinet Regulation No. 238 mentions spark arresters only for vehicles (388, 390, 403), there is no requirement for chimneys; Cabinet Regulation No. 238 loses force on 02.01.2027 checked 4 November 2026