Replacing internal wooden lintel

[nicck]

I have a wooden lintel to replace.

It is internal and crosses a window gap.
This is a substantial lintel of approximately 2000mm gap length depth of 300mm and height of 150mm.

It support the above floor joists in 4 places.
Should this be replaced with a set of concrete lintels or box steel ones, or an RSJ?


View media item 35607

 

[tim00]

Post more pics ( one from the outside ) to give a wider, larger sense of what is going on in that room

Is this the only frame with a wood lintel? How old is the property?.

 

[nicck]

It is circa 1900.

The outside of the property shows no signs of movement at all.
It is a granite property and there is a granite lintel above the window.
All the windows have an inner wooden lintel to hold the joists of the above floors.

The walls are solid granite, not rubble filled.
The laith and plaster has been wall stripped and the celling will be stripped back about 2 feet. The joists were replaced form above but they left the old wooden lintel in.

 

[tim00]

Thats helpful,but more, right way up, pics are needed.
1. why were the joists replaced?
2. are the lintels fungus damage free? Dig into their bearing ends with a screwdriver.
3. presumably we are talking about chamber joists here?
4. why is the ceiling being stripped back 2ft?
5. what do you mean by "lath and plaster has been wall stripped"?

 

[^woody^]

You can replace with a standard steel box lintel, or concrete, or a steel beam - it does not matter

A concrete lintel would be the cheapest and heaviest and more awkward, unless you use a couple of 65mm lintels one on top of the other

A steel beam may be cheaper than a box lintel, but a box lintel slightly lighter to lift

 

[nicck]

Thanks for advice.

Pics are difficult just now because the area has been sheathed in plastic to reduce the dust spreading. So I can't get far enough away to get a proper picture.

1. why were the joists replaced?
there was dry rot from the flat above.
they replaced the rotted ends but not the lintel.

2. are the lintels fungus damage free?
no, the lintel is fungused which is why it is being replaced.
the room has been rot treated before and all examination indicate the rot was in the property above and localised to a relatively small area.

3. presumably we are talking about chamber joists here?
yes.

4. why is the ceiling being stripped back 2ft?
two reasons, to give full access to replace the lintel.
to ensure that all the rot has been removed.

5. what do you mean by "lath and plaster has been wall stripped"?
the wall below the lintel to each side of the window is old lath and plaster.
it was stripped to check if the rot had travelled further than the lintel and we decided just to strip the whole wall so that insulation could be added.

I measured the lintel accurately and it is 1600mm on the largest par of the gap. With a 200mm overlay. It is 250mm deep and 150mm high.

I am happy to use the easiest of a standard steel box lintel, or concrete, or a steel beam. I would like to get some advice on the structural strength to choose.

The weight should not matter too much for fitting, obviously lighter is easier. More importantly is size and manoeuvrability as this has to go in from below.

Read more: http://www.diynot.com/forums/viewtopic.php?p=2047350#2047350#ixzz1Rui3NImd

 

[tim00]

So there was a previous outbreak of dry rot ( d/r) centred in your flat and spread to the flat above. It was treated in the past but a fresh outbreak occurred. Is work on the d/r ongoing in the flat above? How certain are you that you have revealed all the d/r and the cause of the outbreak? Are professionals involved with chemical treatments?

1. Check the joist tails are bolted on, (not just screwed or nailed) and capped and treated in the masonry, bearing pockets.
4. Presumably, you can now see where and how the bolt-ons connect? 5. 5. So the wall surface is down to masonry - no carcassing or skirting plugs or nailing blocks left in the wall? Before the PVC frames did you have wood frames?

I ask all these Q's because i've seen these type of jobs never quite cleared up and much mats and money wasted. The lintel issue(s) are straightforward from what you say,.

 

[nicck]

So there was a previous outbreak of dry rot ( d/r) centred in your flat and spread to the flat above.

No, sorry I have been unclear. The rot occurred in the flat above from a leaking sink and spread to the floor between the flats.
The flat above treated their rot, replaced their floor boards and the rot affected joist ends. Then everything was sealed up and they sold it.

How certain are you that you have revealed all the d/r and the cause of the outbreak? Are professionals involved with chemical treatments?

The walls have been striped floor to ceiling to the granite and the rot is not visible below the level of the lintel. Directly above the rot was a known leak, the water source has been removed. Once the wood lintel is replaced with concrete or steel the surrounding area will be rot treated.

1. Check the joist tails are bolted on, (not just screwed or nailed) and capped and treated in the masonry, bearing pockets.

When the ceiling is stripped back I will be able to see this, where they meet the wall they are capped.

4. Presumably, you can now see where and how the bolt-ons connect?

Not until the ceiling is stripped back.

5. So the wall surface is down to masonry - no carcassing or skirting plugs or nailing blocks left in the wall? Before the PVC frames did you have wood frames?

Wall is stripped bare to the granite.

 

[hotrod]

Beautiful coving btw. I know you've said internal, but will any part of the new lintel be visible externally?

 

[nicck]

Thanks,

The coving is pretty good and in reasonable condition for 100 years old.
There are a few bumps on it and I just cant imagine how you go about damaging coving in a room that has a 10 foot high ceiling.

The new lintel will be completely internal and not be visible at all.

 

[hotrod]

Some people just don't appreciate great workmanship.

Regarding replacing your lintel you're going to have to use 2 side by side because there's not a standard section size available off the shelf that will suffice. Your options are to either use*:-

1. 2 n.o. 100*150mm @2100mm concrete lintels
2. 2 n.o. 100*150mm Box lintels - such as the HDBOX/K-100:-

http://keystonelintels.com/standards/box_heavy.htm

*In all probability these are going to provide sufficient support but it's impossible to tell from your photos / the details you have provided.

You've also got the option of using steels as you mentioned in your first post. If it were me I would opt for the box lintels.

hth

 

[nicck]

The cornicing has been taken down in sections.
The old lath has been stripped from it and the old plaster, which it was embedded in has been sanded. Not it is being painted with an anti-fungicide.

The removal operation was quite successful, unfortunately this was the worst damaged section to begin with and some cracks were already there which meant pieces broke off.

3 out of 5 sections are perfect, two have minor damage.

I am trying to preserve as much of the original character as possible and am quite pleased with the way it is going so far. This cornicing is 100+ years old so I feel at least an attempt to save it should be made.

What additional details would be required to give more information on the support required?.