A sheaf of architectural plans lie spread across the desk of Maher al-Batroukh. The concept is simple: a three-storey school for 600 disabled children.
But it has become the most ambitious project of his engineering career, for this is Gaza after two years of a strict Israeli economic blockade, under which the import of any construction materials are banned. Desperation has prompted innovation: Batroukh's principle building materials are rough bricks made from Gazan clay.
Outside in the baking sun, rows of thick, handmade blocks of clay and hay are lined up to dry, while nearby a digger drops piles of concrete rubble – taken from the ruins of houses destroyed in Israel's January war in Gaza – into the foundation trenches.
It is a compelling demonstration of both the startling, backward slide in development in Gaza and the ingenuity and resilience of its people, who Barack Obama said in Cairo last week were facing "a continuing humanitarian crisis" which "does not serve Israel's security".
Following the Hamas victory in Palestinian parliamentary elections in early 2006 Israel has imposed tightening economic restrictions on Gaza. For the past two years, since the Islamist movement seized full security control over the strip, it has meant a strict blockade under which exports are banned along with all imports, including construction materials such as cement, metal, glass and wood, except for a limited amount of food and humanitarian supplies. Egypt has joined in, keeping its Rafah crossing into Gaza largely closed too.
The closures have meant barely any rebuilding has taken place in Gaza since Israel's devastating war nearly six months ago, which killed around 1,400 Palestinians and 13 Israelis and destroyed thousands of Gazan homes and businesses. The lack of equipment is even jeopardising a landmark $75m sewage project championed by Tony Blair, according to the World Bank.
"The closure doesn't give us cement and steel, but life must continue," Batroukh said. "So we decided to build from clay."
For the project at the Mabarra al-Rahma school in Shujaiyeh he studied mud-built designs on the internet to pick up long-forgotten techniques. He had the bricks tested by university engineers, until he proved they were tougher than cement blocks, and is now having a brick-making machine built that will shape them more precisely and bake them more quickly than the current 10 days drying in the sun.
Supporting pillars will be of clay bricks with a core filled with concrete rubble and clay. Ceilings will be domed so the bricks will hold themselves in place without the need for cement. A plaster of lime and charcoal powder together with water run-off slopes should prevent the whole structure disintegrating in the winter rains. By his calculations the school will cost barely half as much to build as a conventional cement and concrete structure of the same size.
"We are looking at it as if these closures will continue for 100 years. We have to work. We cannot stay like this," he said. "But it is a big challenge."
He is not the only Gazan looking at resourceful new ways to skirt the blockade. A few miles further south, in Al-Bureij refugee camp, Shawkt Najar, the head of environmental health at the local municipality, has designed two new vehicles built from scrap metal, one to collect rubbish, the other to fix street lights. The two are trailers pulled by the municipality's one working tractor and replace a now broken-down, 16-year-old Volvo rubbish truck which could not be properly repaired or replaced because of the blockade.
The trailers, painted bright yellow, are simple but effective, relying on recycled hydraulic pistons powered by the tractor. They head out each day, for rubbish collection in the morning and light repair in the afternoon, trundling through the narrow alleys of the camp, home to 38,000 people.
"We feel proud that we found a way to defy the situation," said Najar. "It is difficult, but we must survive. When people see this collective punishment against them they have to find ways to live their lives. "
After the war in Gaza nearly $5bn in aid was pledged by the world to help the Palestinians, particularly to rebuild Gaza. But because the blockade prevents the entry of much-needed materials there has been barely any reconstruction.
Israel as well as some international aid agencies, particularly those relying on US government donor money, and the Palestinian Authority based in Ramallah, on the West Bank, are also reluctant to do anything that might strengthen Hamas.
"Parties to the conflict and the international community have, to varying degrees, prioritised their own political objectives over people's rights and needs, leaving Gazans sitting on the ruins of their homes," the aid agency Oxfam said in a recent assessment. "By attempting to isolate Hamas, the government of Israel and key international donor governments and institutions have in fact isolated the people of Gaza, thereby reducing chances of securing a peaceful, just and durable resolution to the Israeli-Palestinian conflict."
Hamas has tried to launch its own reconstruction programme, offering cash handouts of a few thousand pounds to those whose homes or businesses were destroyed. Ibrahim Radwan, the Hamas deputy minister for public works and housing, said outside help was welcome but should be coordinated with the Islamists' de facto government – though there is little chance of that happening.
His team has carried out detailed surveys of all houses damaged during the war, assigning each a code and listing the scale of the damage, its cause and the size of the property involved with a view to an eventual compensation payment. They estimate 4,000 houses were totally demolished and 50,000 partly damaged – perhaps 10,000 of which were severely damaged.
So far his workers have cleared some rubble and tried to repair some buildings. "Rebuilding needs open borders, free movement," he said. "We have here people who need shelter. Our first priority is to ease their agony and give as much relief as possible," he said. Israel had imposed restrictions on Gaza in the past, he said, before Hamas came into power. "People understand that the real cause of their suffering is the occupation."
However, although the movement retains its core of support, some Gazans are now speaking more openly of their frustration with Hamas. Perhaps in acknowledgement of this, Hamas has quietly but noticeably moved to halt rocket fire by militants into southern Israel, which Israel said was the reason for its January war and which even some Hamas moderates have admitted privately for years was a dangerously mistaken policy.
In a dirt patch in Beit Lahiya, several families left homeless during the war are still living in tents. Taghreed Abu Tabaq, 35, has three tents, each neatly arranged inside with a small cooking area, the family television and thin mattresses for beds. She lives here with her husband, who is blind, and their eight children. They have not received money from Hamas, only blankets, food parcels, mattresses and other help from the Red Cross.
"I blame the Arabs and the Jews for what's happened to us," she said. "I blame Hamas for firing the rockets and the Israelis for responding out of all proportion against everyone and everything. I'm sure the world understands our situation, but what are they doing for us? This suffering will continue."