The cost of construction materials has gone through the roof — if you can still afford a roof, which isn’t very affordable right now.

All I wanted to do was build a modest roof over my modest deck at my modest house.

But a year of government pandemic policies and the law of unintended consequences have foiled my little dream by driving up the price of lumber.

According to Fortune, the costs of items like plywood and 2x4s increased 193 percent since last spring 2020 and are not done spiking yet.

Thanks to a perfect storm created by the COVID pandemic, two things conspired to drive up the price of lumber.

First, strict government lockdowns and public health restrictions at sawmills slowed down production and limited supply.

Second, America’s vast army of weekend do-it-yourselfers was isolated at home for months with lots of spare time to finally tackle their DIY construction projects.

Making things worse, Fortune says, record low interest rates and a historically tight inventory of existing housing drove up demand for new houses — and therefore lumber.

According to Business Insider, the National Association of Home Builders (NAHB) found that higher lumber prices have raised the price of an average new family home by nearly $25,000 since last April.

That’s no big deal, according to the fat cats at Goldman Sachs, because interest rates are so low that the cost to finance the higher borrowing for your new McMansion is still relatively affordable.

But higher lumber prices are a big deal if all you want to do is build a modest porch roof over your deck.

I could have had it built last spring for about $8,000.

But with a ½-inch 4×8-foot sheet of plywood costing nearly $60 at Lowe’s, it’s anyone’s guess what my roof might cost me now.

And that’s if I can get a busy contractor to come over to give me an estimate.

My failure to anticipate the current spike in lumber prices is nothing new.

I’ve never had much luck foreseeing national trends caused by well-meaning but predictably harmful government policies.

In 2001, before the 9/11 tragedy, I nearly bought a half-duplex for $165,000 just outside of Old Town, Alexandria, Va.

The owner was eager to sell — there were no lines of people outbidding each other yet. But I wasn’t sure if I’d be staying in the D.C. area, so I passed.

I had no idea that the Federal Reserve would soon be slashing interest rates and pumping an unimaginable amount of dough into the economy to stave off recession.

I also had no idea that qualifications for mortgage loans would be lowered and overly aggressive mortgage firms would use interest-only gimmicks and all kinds of accounting tricks to qualify anyone with a pulse for a $400,000 loan.

Boy, did all that easy money cause housing prices to soar in the 2000s.

In 2005, a duplex in Alexandria nearly identical to the one I nearly bought in 2001 sold for $465,000 – an increase of $300,000 in only four years!

Of course, that real estate bubble famously popped in the Great Recession of 2008.

Some smart people saw that coming, sold their houses and cashed in their profits, but I, of course, wasn’t one of them.

I’m just not good at predicting the future. I’m just a guy who can’t bring himself to pay ridiculous premium fees to build a lousy porch roof.

Tom Purcell, author of “Misadventures of a 1970’s Childhood,” a humorous memoir available at amazon.com, is a Pittsburgh Tribune-Review humor columnist and is nationally syndicated exclusively by Cagle Cartoons Inc. Send comments to Tom at Tom@TomPurcell.com.