Glulam Beam - Checking Problem

rScotty · Aug 2, 2023

Pettrix said:
It appears that is what the engineer will require. Running long lag/timber bolts through the bottom to bring that bottom glulam back to where it was and prevent any future issues. It did NOT delaminate (which is a different problem all together) but the bottom board was initially glued into place and it checked so it will be mechanically connected with the lags/screws.

Before you sign off on it, it may be worth keeping your options open. As I look at those photos again there seem to be separations beginning between other layers in addition to the large one. It may just be an artifact of the photograph - but you may want to take another look. If the beam was laminated too wet it is hard to see how that is going to improve with lag bolting.

Maybe it is acceptable to their engineer. My own experience with glulams is limited to one project. If it were mine I'd probably accept an opinion from a licensed professional engineer's as long as it included guarantees into the future.
rScotty

Iftisam Mulani · Aug 3, 2023

Pettrix said:
I had some glulam beams installed on my new house build. I am in Arizona so it was hot & dry and the beams were installed in less than 1 week after being delivered. The roof was put on and now I am noticing some checking in that glulam beam. I was told that checking is normal, especially in a hot climate but I feel uneasy about it so I contacted the glulam manufacturer and they are looking into it.

Can a glulam beam be fixed on site/installed? I've seen some online photos of them using epoxy and lag bolts to shore up the beam.
On mine, it's the bottom board that has checking in it. I know that board is under tension since it is the bottom board.

Any help would be appreciated...

you're correct that the bottom board of a glulam beam is typically under tension. However, the glulam's overall structural design takes this into account. If the manufacturer or an engineer determines that the checking is a concern, they will advise on the appropriate steps to take.

To minimize the development of checking in the future, you can consider applying a protective finish or coating to the glulam beams. This can help reduce moisture absorption and minimize the expansion and contraction that contribute to checking.

Regardless of the outcome of the manufacturer's assessment, it's a good practice to periodically inspect your glulam beams for any changes or signs of deterioration. Early detection of any issues can help prevent further complications.

ponytug · Aug 3, 2023

Pettrix said:
It appears that is what the engineer will require. Running long lag/timber bolts through the bottom to bring that bottom glulam back to where it was and prevent any future issues. It did NOT delaminate (which is a different problem all together) but the bottom board was initially glued into place and it checked so it will be mechanically connected with the lags/screws.

If it were me, I might enquire about injecting epoxy into the crevices before installing the lag bolts. Belt and suspenders and all that.

All the best,

Peter

Pettrix · Aug 3, 2023

yooperdave · Aug 3, 2023

Did you get a balanced lamination - tension lams on both top & bottom?
Otherwise did you make sure the beam was not installed upside down?
Upside down has half the bending capacity - unlike LVL and PSL.
Assuming your beams are not yet fully loaded.
I would not accept the beam as installed.
You could add steel side plates and long vertical lag screws after shoring to get the load off the beam- but why for brand new?

Good Luck

I used to be a glu lam structural engineer back in the 1980's.

Yooer Dave

Pettrix · Aug 3, 2023

yooperdave said:
Did you get a balanced lamination - tension lams on both top & bottom?
Otherwise did you make sure the beam was not installed upside down?
Upside down has half the bending capacity - unlike LVL and PSL.
Assuming your beams are not yet fully loaded.
I would not accept the beam as installed.
You could add steel side plates and long vertical lag screws after shoring to get the load off the beam- but why for brand new?

Good Luck

I used to be a glu lam structural engineer back in the 1980's.

Yooer Dave

The top of the beam was marked "TOP" in black lettering and they were installed the correct side facing up.

As mentioned, since the roof is installed, I cannot simply remove the beams without demolition of the roof. A cost of $80k + to do so.

My only option is to repair it.

Glulam engineer stated that he believes the other 2 beams are okay and structurally fine, just some checking due to dry hot air. The one beam will be repaired and I should have the details on that this week. Initially, it appears long 10" threaded timber screws from the bottom to shore up the bottom board, probably spaced 12" staggered. He also stated that if the other 2 beams were structurally compromised he would recommend fixing those also as the company doesn't want any issues should those beams fail. They always error on the side of caution and will do repairs to avoid possible failure issues later on.

yooperdave · Aug 3, 2023

Pettrix said:
The top of the beam was marked "TOP" in black lettering and they were installed the correct side facing up.

As mentioned, since the roof is installed, I cannot simply remove the beams without demolition of the roof. A cost of $80k + to do so.

My only option is to repair it.

Glulam engineer stated that he believes the other 2 beams are okay and structurally fine, just some checking due to dry hot air. The one beam will be repaired and I should have the details on that this week. Initially, it appears long 10" threaded timber screws from the bottom to shore up the bottom board, probably spaced 12" staggered. He also stated that if the other 2 beams were structurally compromised he would recommend fixing those also as the company doesn't want any issues should those beams fail. They always error on the side of caution and will do repairs to avoid possible failure issues later on.

Keep a close eye on the deflection. The beams should be shored with a camber up prior to reinforcing. Lag screws need to extend well beyond the neutral axis of the beam. Try not to compromise the tension lams or they will crack as well. The beams should have had a low moisture content to begin with. I am not so sure that they 'dried out'.

BigGG · Aug 3, 2023

yooperdave said:
Did you get a balanced lamination - tension lams on both top & bottom?
Otherwise did you make sure the beam was not installed upside down?
Upside down has half the bending capacity - unlike LVL and PSL.
Assuming your beams are not yet fully loaded.
I would not accept the beam as installed.
You could add steel side plates and long vertical lag screws after shoring to get the load off the beam- but why for brand new?

Good Luck

I used to be a glu lam structural engineer back in the 1980's.

Yooer Dave

Can you elaborate? Are some lams pre-tensioned or . . .? I always thought these were just glued and clamped together.

Pettrix · Aug 3, 2023

yooperdave said:
Keep a close eye on the deflection. The beams should be shored with a camber up prior to reinforcing. Lag screws need to extend well beyond the neutral axis of the beam. Try not to compromise the tension lams or they will crack as well. The beams should have had a low moisture content to begin with. I am not so sure that they 'dried out'.

I will do. I believe he wants to use these Simpson Timber Screws. 2,000 lbf of tension and 1,400 lbf of shear strength. Initial install sounds like 12" oc staggered but I don't have the detail yet

Here are some pics of the 4x6 top plates. It was solid when bought/delivered and checked within a few days after being installed. This is very common for lumber out here in Arizona.