Combi in the loft

[David]

In article , IMM writes

You think the ladder structurally supports the gable end? what a plonker

[David]

He means the extension piece that is built through the gable end to support the barge board, soffit outside, John thinks this holds the gable end together

[Andy Wade]

He's referring to the 'gable ladder' construction used to provide an overhanging verge at a gable end. This consists of several short horizontal timber members (running parallel to the ridge on an simple roof) nailed to the end truss, with the barge board nailed on the outside ends. Seen before the undercloak, felt and tiles go on this does look like a crude sort of ladder. When the gable end brickwork is built up it surrounds the 'rungs' of the ladder and helps tie-in the end truss to the masonry. But there should also be steel lateral restraint straps between the inner leaf of the wall and (at least) the first two trusses at each end (AIUI).

50 kg (only 0.5 kN) seems to me to be a pretty negligible load to hang on a sound brick/block wall (unless you're talking about a narrow section between window or door openings, which is hardly likely to apply in a loft). And the weight's going to be fairly close to the wall so the overturning moment will not be large.

[IMM]

The question marks prove it.

[IMM]

Oh a mentalist!

[IMM]

Mentalism again.

[Andy Hall]

If you mean the timber construction to support an overhang if one exists, it doesn't of itself add to the structural integrity of the gable end wall

.andy

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[David]

In article , IMM writes

On who's part? isn't that what you think?

[IMM]

The lateral wood support (usually a long plank) that ties in all the trusses usually has the steel lateral restraint nailed to it and the other end of the right angle of the steel restraint either screwed or cemented in to the gable end wall. The steel restraint can be quite long and go over the length of three trusses. These steel restraints help join the gable to the roof. They also help to keep it doiewn in high winds. Have a look around Wickes as they have them there.

If some roofs do not have them., older roofs may not, then it is worth fixing a number of these metal restraints and fitting them. Wind speeds in the UK are rising and these restraints may mean the difference of your roof lifting off or not. They also prevent an old gable wall creeping outwards if the ground conditions change.

Some sense at last. This bunch seem to think a gable end sits there unconnected to anything else and is so feeble, complete with feeble foundations, it can't hold a combi. I despair at times.

[IMM]

incorporated

Stop babbling.

[Andy Hall]

I know exactly what you mean, but not by that name.

Of itself it is not lending support to the wall.

For a party wall, if also structural, then I don't see an issue. Otherwise.......

.andy

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[James]

I have no specialist knowledge, but I wondered if it is possible for the weight to be taken by the loft floor rather than the wall. I know such floors are not meant to take weight, but they are nonetheless used to house equally heavy water tanks. Or does the placement of such tanks rely upon a structural wall underneath?

James

[Tim S]

The foundations are the same as you say. Problem is with top ends of walls which don't support anything above.

I'm not a civil engineer - I'm thinking this through as a physicist, so obligatory hypothetical situation - but bear with me here:

Take a pile of bricks and construct a 6ft high by say, 4ft wide, 9in thick dry wall (no mortar or other filler) on a stable level surface. Kick the bottom - I would wager a fiver you'll hurt your foot before you move any bricks due to the weight holding them in place. Try nearer the top - should be able to knock out a load of bricks easily because you only need enough sideways force to overcome a little friction.

Add mortar - that will scale the strength up by providing adhesion and better interlocking, but strength is still a function of internal load - and the top end of a wall carrying nothing is thus considerably weaker than a loaded wall or the base of the same. The combi will be hanging off one side of the wall giving you a significant turning moment which only needs to overcome the adhesion of the mortar and the weight of a few feet of bricks.

I have no idea how heavy a combi is - but I'd consider it worthy of further investigation before hanging it up on a gable end. What's the typical weight of a small combi out of interest - and how deep is one?

I won't contest that you've done it and it nothing fell off - but I wouldn't be so happy about doing it myself without a second opinion.

Cheers

Tim

[VisionSet]

I see no reason why not, except that is is easier if there is good access underneath for pipework connection. Boilers tend to come on a wall mounted jig, which makes life easier. The load bearing wall that supports the party wall will be very close though so that wouldn't be a problem. And yes tanks are supposed to be close to or on a supporting wall.

I don't think it will be a problem, but I'll ask uncle architect first.

-- Mike W

[Capitol]

He did say it was a party wall. in a 1930's house this would normally be double brick and not a problem.

Regards Capitol

[Andy Hall]

Mmm I know, and did intimate that a structural party wall probably would be. My doubts were in relation to gable end walls which may be a different situation.

.andy

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[IMM]

Does that mean you are not going to lean on this wall?

[John Rumm]

Out of curiosity, exactly what do you think that means?

[Andy Wade]

It seems to be IMM-word-of-the-month.

Dictionary.com gives two definitions:

1. Parapsychological activities, such as telepathy and mind reading.
2. The belief that some mental phenomena cannot be explained by physical laws.

The Concise OED also has two:

Mentalism n. (Philos.) doctrine that mind, and not the material world, is real; (Psych.) doctrine that the mind may be studied by introspection; so ~ist(2) n.

[Andy Hall]

It's nearly October, so not long until we have the next WOTM, and state-sponsored heating solution for the terraviduated proletariat.

The second definition sounds uncannily like IMM's modus operandi.

.andy

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