Anyone laminated lead sheet to plywood? What adhesive?

[Brian Elfert]

I am looking at possibly laminating lead sheet to plywood for a project. What adhesives work for this? The big issue is the temperature of the plywood can get to 250F for short periods. Neither contact cement nor epoxy can handle those temperatures. I do not have a way to spray any adhesives.

[Richard Coers]

I'm guessing you will also have trouble with the plywood. I don't think you can get the ignition point that low, but can't be good for the glue with lots of cycles. The thin plywood on the roof of my 50s ranch sure didn't do well from a poorly ventilated attic.

[Paul F Franklin]

There are plenty of high temperature epoxies available, rated to 500 or 600F. Whether they will bond lead to plywood is a question for the manufacturer, and even then, getting dissimilar materials to stay bonded over temperature cycles will likely be a challenge, given the likely differences in expansion coefficients. If it does stay bonded it may bow with temp changes. And as Richard points out, even the plywood is suspect at those temperatures.

[Joe Jensen]

Seems like you might want a thin advanced insulation between them. Some alternate very thin layers of metal and paper to make a super insulation. The lead will hold heat which would make the 250 time longer. Do you have time to make some test pieces before doing the whole thing?

[Brian Elfert]

I am building an enclosure for a 12.5 KW diesel generator. The radiator will be mounted outside of the enclosure to reduce heat in the enclosure.

There will be a good size squirrel cage blower running while the generator is operating so the temperature should probably be under 150 degrees while running. The issue is heat soak once the generator turns off which also turns off the blower. I don't have a real good way to keep the blower running after shutdown unless I add a temperature switch to the blower.

[Joe Jensen]

Why the lead?

[Jamie Buxton]

So you’re using the lead to reflect sounds. You might look into “mass loaded vinyl”. It is flexible vinyl sheet loaded with lots of something heavy, developed specifically for sound deadening.

You also might consider using backer board to line your enclosure. This is cement board used as a substrate for tiling. Home Depot and the like sell it. I’m pretty sure it will withstand your temperature regime.

[Lee Schierer]

I am building an enclosure for a 12.5 KW diesel generator. The radiator will be mounted outside of the enclosure to reduce heat in the enclosure.

There will be a good size squirrel cage blower running while the generator is operating so the temperature should probably be under 150 degrees while running. The issue is heat soak once the generator turns off which also turns off the blower. I don't have a real good way to keep the blower running after shutdown unless I add a temperature switch to the blower.

There are lots of ways to reduce noise transmission that don't involve lead. They make a sound deadening foam (https://www.secondskinaudio.com/sound-deadening/damplifier-pro) that is made for that specific purpose that is self adhesive on one side. As far as your blower goes, put it on a separate circuit with a heat sensor to turn it on and off.

[Malcolm McLeod]

... put it on a separate circuit with a heat sensor to turn it on and off.

Or perhaps just a off-delay timing relay: https://www.mcmaster.com/off-delay-relays/ (lots of sources - search "off-delay relay"). Blower runs while the generator runs, then continues after generator cut-off for however long the timer is set for.

[Brian Elfert]

Or perhaps just a off-delay timing relay: https://www.mcmaster.com/off-delay-relays/ (lots of sources - search "off-delay relay"). Blower runs while the generator runs, then continues after generator cut-off for however long the timer is set for.

The problem is how does the timer know when the generator has stopped putting out power?

[Brian Elfert]

There are lots of ways to block sound. It has been recommended to me to laminate lead sheet between two pieces of plywood to block the low frequency noise from the generator. It is probably the density and weight of the lead that helps block the low frequency sound.

[Adam Herman]

Or perhaps just a off-delay timing relay: https://www.mcmaster.com/off-delay-relays/ (lots of sources - search "off-delay relay"). Blower runs while the generator runs, then continues after generator cut-off for however long the timer is set for.

off delay timers look for a signal to start the timer, it will run for say, 10 min after the signal is received, such as hooking it to the +12 for the fuel pump, starting relay, ignition coil or similar.

[Adam Herman]

There are lots of ways to block sound. It has been recommended to me to laminate lead sheet between two pieces of plywood to block the low frequency noise from the generator. It is probably the density and weight of the lead that helps block the low frequency sound.

lots of layers of different densities is the way to go, though i am not sure lead and ply are necessary. layers of foam and drywall or cement board may be easier to construct, and use green glue between, i bet this will be cheaper, more effective and easier to build. most of the noise will come from your vents, like those with some kind of egg crate foam or similar, depending on how far you want to go.

[Steve Rozmiarek]

Would that insulation that they put under car hoods work? Something like "Design Engineering 050130 Boom Mat under hood acoustic lining" might be better. This stuff is self stick and good to 275 degrees.

[Frank Pratt]

Nobody uses lead for sound attenuation anymore. A couple of layers of 5/8 drywall with Greenglue between works great. Before building something like this it's best to just dive down the rabbit hole & learn more about it. There are so many myths & misconceptions and some things that seem intuitively would work will actually make things worse.

[Brian Elfert]

It sounds like I should just try to find an acoustical engineering firm that is interested in doing a smaller job, but I still figure it will cost several thousand dollars.

[Malcolm McLeod]

off delay timers look for a signal to start the timer, it will run for say, 10 min after the signal is received, such as hooking it to the +12 for the fuel pump, starting relay, ignition coil or similar.

I don't want to divert from Mr. Elfert's soundproofing topic (too much), and maybe just semantics...?????

I think you are describing the on-delay relay function... the input 'ON' drives the timer; when timer reaches setpoint, the contacts change state. If the input drops out, the output contacts reset (to normal state) immediately.

With off-delay relay, the input 'OFF' drives the timer. The contacts change state immediately when the input goes 'true' (ON). When the input goes OFF, the timer starts. Only when the timer times out, does the output reset (to normal state).

[Joe Wood]

I think mass loaded vinyl would be a good choice, here's one outfit
https://www.homedepot.com/p/Xtrm-Ply-SoundSafe-Mass-Loaded-Vinyl-MLV-4-5-ft-x-10-ft-Soundproofing-Acoustic-Barrier-Roll-7102-11054-10/304268301

[Walter Plummer]

If you are putting it between two sheets why not just screw everything together? No glue to worry about, reversible if something goes south.

[Jamie Buxton]

I just looked up a 12.5 kw diesel generator, and found one which is 50”x25”x35”. It weighs a bunch too — probably installs with a forklift. And probably needs elbow room around it in the enclosure. You might want to make the walls concrete. The high mass of the concrete will do a good job of containing the sound. But the engine is going to be putting out a lot of heat, so there’s going to be air circulating through the enclosure, and sound will escape through those air inlets and exhausts.

[John C Bush]

Check out marine sound and temp insulation dense foam. worked for sailboat engines and gensets

[Brian Elfert]

I just looked up a 12.5 kw diesel generator, and found one which is 50”x25”x35”. It weighs a bunch too — probably installs with a forklift. And probably needs elbow room around it in the enclosure. You might want to make the walls concrete. The high mass of the concrete will do a good job of containing the sound. But the engine is going to be putting out a lot of heat, so there’s going to be air circulating through the enclosure, and sound will escape through those air inlets and exhausts.

This generator is going into a coach bus converted into a motorhome. The generator is 36-1/4" long by 20" wide by 24" tall. It weighs 531 pounds. No fuel tank as it draws from the main diesel tank.

I'm not going to be using something like a concrete enclosure due to weight. The weight of lead and plywood is already pushing it. Intake and exhaust air will go around corners and such to greatly reduce the noise transmission. The radiator is mounted elsewhere so the ventilation needed isn't all that much.

[Tim Janssen]

This generator is going into a coach bus converted into a motorhome. The generator is 36-1/4" long by 20" wide by 24" tall. It weighs 531 pounds. No fuel tank as it draws from the main diesel tank.

I'm not going to be using something like a concrete enclosure due to weight. The weight of lead and plywood is already pushing it. Intake and exhaust air will go around corners and such to greatly reduce the noise transmission. The radiator is mounted elsewhere so the ventilation needed isn't all that much.

Why not duplicate what they do in those motorhomes!

[Brian Elfert]

Why not duplicate what they do in those motorhomes!

A typical production motorhome uses a generator already in an enclosure. My generator is not in an enclosure.

High end motorhomes built on bus chassis often used lead sheet in their generator enclosures combined with foam.

[Mark Hill]

I've used SikaFlex -1A to secure zinc sheet to Advantech and MDF substrates with great results. Bet it would work on plywood and lead.

https://usa.sika.com/en/construction/adhesives-sealants/joint-sealants/architectural-sealants/polyurethane/sikaflex-1a.html

[Brian Elfert]

If you are putting it between two sheets why not just screw everything together? No glue to worry about, reversible if something goes south.

My thinking is I wouldn't want to poke a bunch of holes in the lead sheet to let sound through. I might be way off base on that. Screws would certainly be easier.

[Jerry Bruette]

McMaster-Carr sells several types of sound absorbing panels and sheets. No need to make your own.

[Chris Tolbert]

I am building an enclosure for a 12.5 KW diesel generator. The radiator will be mounted outside of the enclosure to reduce heat in the enclosure.

There will be a good size squirrel cage blower running while the generator is operating so the temperature should probably be under 150 degrees while running. The issue is heat soak once the generator turns off which also turns off the blower. I don't have a real good way to keep the blower running after shutdown unless I add a temperature switch to the blower.


can you add a shutdown timer to the fan? Something that keeps it running for, say, 20 minutes after the genset shuts down?

[Tom Bender]

Using fuel from the vehicle tank is a great way to keep the fuel fresh. I like that idea.

Adding 531 pounds to the vehicle seems extreme. Then adding lead,,,,well we have different approaches to camping.

Loaded vinyl sounds reasonable and doesn't add the toxicity of lead to the works of man.

[Bill Dufour]

rockwool insulation will take heat no problem. Fibreglass has to be the white no glue kind or it can burn. have you considered liquid tanks such as fuel, water, sewage etc. Make sure it is spring loaded so it does not vibrate the entire chassis.
Some police special cars insulate the battery by placing it inside a special doughnut shaped windshield washer fluid tank
Bill D

[Alex Zeller]

Why not just use a product made for it? Sound deadening adhesive sheets for high temps are used all the time in the automotive industry. They insulate for both noise and sound so they should protect the plywood from the heat.

Something like this: https://www.amazon.com/Thermo-Tec-14620-Heat-Sound-Suppressor/dp/B004PILLZG

[ED Budzinski]

Look into "Soundproof Cow" . Maybe those people can help you .