Fire Pit in decking

21 Feb 2014
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United Kingdom
Im thinking about installing a fire pit into decking, Im posting this in the building forum because im guessing you guys will have a better idea about materials to contain heat than the garden forums. If your not sure what a firepit is, its basically a brick or stone outdoor fire, they dont seem so common in the uk but seem to be popular in the states

they can look like this:


my idea is to build a smallish one at the back of the house that comes up through the decking, at the location of the pit, the decking will be at most 25cm from the floor, maybe a little more when ive taken up the old block paving.

I will have the firepit come up one or two bricks from the level of the deck, but the fire will be much lower down inside. I wondered what kind of materials id be looking at building the pit with that would be able to protect the decking around the pit from heat.

also does anyone know of any laws around fires and proximities to the house structure especially in this configuration where they are permanent and not a chiminea etc

The bottom of the pit is a layer of sand on top of gravel or hardcore for drainage so shouldn't fill with water if done correctly as the base of the fire should be about level with the original garden floor.

I will then build a cover from the same decking so i can cover it when not in use.

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first off im not familiar with fire pits however i would give some thought to the height you come through the decking
at a couple of course in height you need to look at the fact someone may trip and fall into it.
at a couple of course in height you need to look at the fact someone may trip and fall into it.
Obviously the guy can not have any children and has no intention of ever having any around whilst the fire is lit. Correct?

I'd be thinking along the lines of getting air to the base of the fire. Having a liner that is removable so that the ashes can be easily disposed of. Making whatever hole in the decking large enough so that there is a masonry barrier betwixt the wood deck and the fire pit etc.

The base of the pit being lined with sand etc is pointless because after two fires all this will be gone once you have cleaned out all the ash. You also need a rain cover for when you abandon the fire at night to smother it and to stop the ashes turning into mud when it rains.

A lot more thought needed if you are to make this US idea work over here.
I built a permanent barbeque and lessons learned:- A proper conical rain cover is required. this is to keep the brickwork dry. If the brickwork gets wet then the heat from the fire will turn the water content into steam with possible explosive results. The brickwork will expand with the heat and will move about, I used a soft lime mortar, but if you tried to lift a brick out, I am sure you could. A possible solution for this is to line the brickwork with "Celcon" blocks, these will slowly burn away but will keep the outside brick work cooler. As mentioned you need air going into the bottom of the fire. gap between the brickwork and the Celcon blocks? The picture you showed seems to be a fire to keep people warm or if used for cooking, is big enough to cook a whole pig on!! My one was about 3' X 2' with a "keeping hot" shelf above it. Big enough to cook for a dozen or so people. I wonder what will happen if there is a breeze blowing, the smoke will be at a low level and get in the cook's eyes, not to mention sparks blowing about. if its at a low level cooking will be a real pain in the back.
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thanks for the responses so far.

Im not intending to cook on it as as you say it will be too low and smoke would be a problem, it would be for warmth on cool summer evenings sat outside.

At the moment, there is no chance of children in or around it and certainly wouldn't be lit if kids were around on top of that it could be filled in and used as a sand pit for kids if it were needed by someone in the future. however i dont have children at this point, and probably wont do for the foreseeable lol.

on the subject of kids if you had a cast iron chimnea that was burning super hot it would be almost as unsafe if a child fell on it. although granted that the added inability for a child to climb out would not help. but this is the same issue you have around ponds and pools. So a bit of care and common sense should keep every one safe.

does anyone know if concrete is fire/heat retardant? I have some 2 inch thick slabs that i could cut and line the inside with, then build a wall around the outside to look nice, in fact only the parts above the deck need be in brick, so the outside could be built in concrete also?

on top of that I have a huge amount of surplus concrete block paving bricks that i have no use for, would these be any good?

the points about water and rain I have taken on board, i would construct a tight water proof top to sit over it during the winter.

and for the final point, ventilation. in the ones ive seen online, ventilation is usually a couple of holes at the bottom to allow air in. however im worried that hot embers might escape these holes and cause fire issues under the decking. should i be worried and what could i do to mitigate these kind of issues?

the only other worry is proximity to the house, the closest wall will be less than 2m away however this wall is 2 stories, made of brick and has no windows and doors on the whole 2 story span, should i be worries, it seems to me after 2m from a small fire, most heat would just be reflected by the wall.

How about cutting off the bottom 3rd of an oil drum punch holes for air intake and 2 holes near the top to hook it and drag it out to empty
If it were me I'd probably line it with solid engineers built in header bond
I suppose if you really wanted to go for it you could look at fitting a steel tube from somewhere around the drum back upto the surface where you could incorporate the use of a hand bellow.

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