Changing Timber Lintel To Concrete

[DIY-AMATEUR]

First post on here so hello to you all!

I need to change an old timber lintel over my livingroom internal door to a reinforced concrete type to stop the plaster cracking due to the expansion and contraction nature of the timber and the fact that plaster doesn't adhere well to it.

It is a bungalow but the lintel in question is on a single skin supporting wall that runs up to the roofline. I was planning on hiring 2 strongboys to support the blockwork from the livingroom side enabling me to work from the hall side.

Im a little unsure regarding bedding and packing the lintel. The timber lintel is 95mm high but the replacement concrete lintel is only 65mm.

What is the correct way to install the lintel?

1 - Bed of mortar on top of the lintel, offer into place then pack up tight from underneath with slate and then back fill the voids underneath with mortar?

2 - Install lintel dry (no mortar on top) and pack up tight underneath with slate then backfill voids underneath with mortar.

3 - Another way?

Am I correct that if you rely solely on mortar beds top and bottom (no slate) you could get shrinkage issues as the mortar dries resulting in the lintel being loose?

It will be a 1200mm wide lintel giving a 150mm bearing on either side. There are currently no padstones and the timber is sat directly onto the blockwork the same as the concrete lintels are over the other doorways. I think they used timber as it was originally a door with a framed glass panel next to it and probably didnt have a wide enough concrete lintel so just threw the timber in, it was the 60's! The timber lintel is approximately 1600mm wide so might buy the same length in concrete giving larger bearings either side or just stick with the 1200mm lintel and brick in the remaining voids.

Hopefully someone experienced can guide me in the right direction.

Cheers

 

[CJRatch]

Would a 100mm x 100mm concrete lintel with small beds not fit once the wooden lintel and mortar bed are removed? This way you will require minimal packing.

 

[DIY-AMATEUR]

Hi. Thanks for your reply. Ive just measured the timber again and its actually 98mm so the 100mm would physically fit but then only allow a tight mortar bed on either the top or bottom. How would I fit this option correctly?

The timber appears to be sat directly on the blocks with only mortar along the top edge.

 

[DIY-AMATEUR]

Hi all, still not got round to sorting this and now it turns out that when they removed the old glass panel next to the door and bricked it up they never tied it in. I thought there were verticle cracks due to them leaving the skim beads in so had a nice suprise when i found how loose it all was after i pulled the beads out. Blocked it up again with ties on each course for good measure.

Anyway, my dilema is that there is major historic movement which has left the timber lintel 30mm out of level across the opening. Any ideas on what to do, my dad keeps saying just replace it as is with the pre stressed concrete lintel but i keep wanting to put the lintel in level. If i put the lintel in level then i will have to remove another course of bricks above the lintel and then cut some of the bricks down to accomodate the 30mm taper.

I cant fit padstones either as the wall also forms part of the newly finished kitchen. All of the other lintels in the house are just sat on a bed of mortar on top of the concrete blockwork.

Someone please take pitty and guide me through this as ive been trawling the web for hours and cant find anything helpful that is relevant.

Cheers

 

[23vc]

Apols if I’m missing something but can’t you just plasterboard the exposed area in your pics and be done with it? Assuming the timber lintel is only causing problem if it’s plastered directly onto. Which it wouldn’t be if you board it, make good with bonding, blend into existing wall with skim. Or is it bowing/structurally unsound?

 

[tony1851]

Have you thought of re-using that timber lintel. but turning it round through 90 degrees? The way they have installed it, with one piece flat on top of the other is useless. If both pieces are vertical. ie II instead of =, it would be much stronger.

 

[DIY-AMATEUR]

Its not even 2 full pieces of timber, the top one is 3 pieces, cowboy builders! I want concrete anyway mate as the timber one originally cracked and blew the plaster due to its expansion and contraction nature.

 

[Ian H]

What about going back to the 65mm concrete lintel and packing to low end up 30mm?

 

[DIY-AMATEUR]

What about going back to the 65mm concrete lintel and packing to low end up 30mm?

I cant get hold of a 100mm lintel now due to the lead time for delivery as its not a stocked item. My thoughts now are to bring the new blockwork on the pic up level to the opposite side and then remove 1 course of brick above the lintel. Fit the 65mm lintel level on mortar beds and then whiz down dense concrete blocks to infill over the lintel which will alter in size by 30mm as they go from side to side due to the subsided wall.

Does this sound right or will the cut down dense concrete blocks cause an issue? I cant use the existing bricks as the opening is too large on one side (due to lintel being 30mm thinner than existing timber) unless i had 20mm + mortar beds on the first couple. The bricks on the other side would need around 15mm trimming off which would be hard to do hence thinking of cutting the concrete blocks down to the required size.

I know im over thinking it but i cant find any info for this type of scenario with the subsided wall.

Cheers

 

[^woody^]

Are those blocks tied in every course? If not, avoid any argument that lead to door slamming. You'll need some mesh across that joint.

For the lintel, bed the lintel up and put a timber infil above the frame, or pack the joint with some clay tiles.

 

[DIY-AMATEUR]

Are those blocks tied in every course? If not, avoid any argument that lead to door slamming. You'll need some mesh across that joint.

For the lintel, bed the lintel up and put a timber infil above the frame, or pack the joint with some clay tiles.

Yes mate, i put a screw in wall tie on every course. Bit of a pain getting the blocks in without knocking all the mortar back out though!!!

What mesh are you referring to, just scrim tape when plastering or something fixed to the blockwork?

What do you think about the cut down dense concrete blocks to fill back in above the lintel where i will have removed a course of bricks? The bricks as is are too small one side and too big the other if i fit the lintel level. My dad keeps saying put the lintel in as is (30mm out of level) but i want to level it up.

I was going to fill in between the frame and underside of the lintel with dabbed on plasterboard then bond and skim over.

 

[^woody^]

You can infill with cut blocks, but you may have a job cutting them. Thermalite blocks can be cut into strips with a hand saw.

That vertical joint will crack, so could do with a 100mm galv or stainless steel mesh bonded across in the plaster base coat to control potential shrinkage.

 

[DIY-AMATEUR]

You can infill with cut blocks, but you may have a job cutting them. Thermalite blocks can be cut into strips with a hand saw.

That vertical joint will crack, so could do with a 100mm galv or stainless steel mesh bonded across in the plaster base coat to control potential shrinkage.

I can cut the concrete blocks with a whizzer as long as they are ok to use infilling above the lintel then.

Ive just seen the galv mesh in screwfix so i will throw some of that on when im bonding it up ready for skimming thanks.

 

[DIY-AMATEUR]

Hi all. Ive got my bearing points level for my concrete lintel but this now leaves a tapering gap of 30mm - 10mm between the top of the lintel and the brickwork over due to the new lintel being level in a subsided wall.

I was going to remove the next course of brick above and replace with cut concrete blocks to accomodate the taper. When i removed the lintel though i was expecting to see a hole into the new kitchen but luckily the plastering had separated from the timber lintel and so has not damaged the finished wall in the kitchen. However, if i remove a course of bricks then that will certainly make a big hole into the kitchen.

Basically i need to know can i fill the varying joint of 30mm - 10mm with rammed in mortar to avoid any unnecessary disruption removing another course of bricks or is that too much? I was thinking that stone walling has large beds of mortar so maybe it would be ok.

Cheers

 

[Mr Chibs]

You could dry-pack this gap.
3 x sharp sand, 1 x cement, mixed with just enough water to be able to form a ball when squeezed in your hand... not wet like mortar.
Ram this in the gap, and tamp as tight as possible. This will be acceptable to fill that gap.

This method is used in some underpinning.